In 2002, Reid Hoffman gathered a team of old SocialNet and PayPal colleagues to work on a new idea—a network that allowed professionals to find and connect with one another. Inspired by the defunct Six Degrees business network which rose to prominence in the late nineties and subsequently closed during the dot-com bust in 2000, Hoffman and team set out to build a new, lasting professional network based on identity and connections. As Hoffman explains, he bankrolled the operation at the start to fund the development of the early LinkedIn platform:
“I already had money from PayPal, so I was financing the early portion of it. When there isn't capital in the bank, there is some anxiety over, ‘Is this thing going to fly at all? Are we going to get enough money to even to go to the venture capitalists?’ I personally bankrolled LinkedIn at the start, so that wasn't as much of a concern.”
Just six months after the start of development, on May 5th, 2003, LinkedIn officially launched. After the first week, the site had registered close to 12.5K users. Still, according to the company’s own numbers, growth was initially slow, and some days saw as few as twenty signups.
Nevertheless, within four months, LinkedIn had hit the 50,000 user mark, and the company, behind the bonafides of its founding team and early promise, landed $4.7M in venture capital from Sequoia Capital in its first major financing round. Within a year of launch, they’d reached 500,000 users. In 2006, just three years post-launch, they achieved profitability. Then in 2011, eight years after their initial launch, LinkedIn became a publicly traded company.So how did LinkedIn grow from as few as 20 signups on some of those early days, to where they are today, almost eleven years later, as a publicly traded company with a market cap of nearly $18 billion, and a network of more than 225 million users from 200 countries and 4,800 employees?
The Need for LinkedIn
When LinkedIn launched in 2003, online social networks—though great for dating and connecting with friends—were not efficient meeting places for business. Co-founder Konstantin Guericke explains:
“There was an imbalance among those looking for jobs and those looking to hire, and between those with money to invest and those seeking funding. As a result, these kinds of people built screens around them and used trusted contacts as filters before communicating with others."
A 2004 Forbes article sums up the site’s core concept nicely, explaining that in the business world, “the most critical step towards finding a job, finding an employee or finding a business partner is getting a high quality referral.” Yet referrals aren’t always easy to come by, especially because people typically have no way of knowing who their connections know. LinkedIn draws upon the theory of six degrees of separation—or, the idea that people are six introductions away from anyone they want to meet.
As they’ve publicly acknowledged, the theory of six degrees of separation—the core concept informing LinkedIn—was not original to Hoffman and the team. Rather, it originated from Andrew Weinrich as the principle behind the networking site SixDegrees.com, which launched in 1997. Weinrich was granted a patent on the six-degrees concept in 2001. Six Degrees grew to 3.5 million users before being sold, at the height of the dotcom boom, to Youthstream Media Networks for $125 million in stock.
Within three months, however, the site had been shut down, and it wasn’t long after that until Youthstream was out of business entirely. Nevertheless, the concept behind the site had proven to be worthwhile, which is why LinkedIn, along with others, acquired the sixdegrees patent for $700,000 in 2003. It forms the basis of their IPO portfolio.
Although they took their core concept from Six Degrees, LinkedIn differentiated themselves from the defunct site as well as other social networking sites popular at the time. Rather than letting users initiate contact with anyone and everyone (as was the case for Friendster, the most popular network at the time), LinkedIn users would be restricted to trusted connections that they knew personally or were referred to through others in their professional network.
This gated-connection system helped curb spam and unsolicited invites, making LinkedIn a safe place for sought-after executives like Marc Andreessen, Jerry Yang, and Pierre Omidyar to participate without being inundated with unsolicited requests, while still allowing the site to function as a powerful tool for users to get introductions through their professional networks.
But the beginning wasn’t all rainbows and sunshine for LinkedIn. As Hoffman points out, the company was founded during an economic downturn, describing the mood in the valley in 2002 as “dot-com winter.” Discussing the ways in which they treated that challenge as an opportunity, Hoffman explains:
“I have a strong belief that starting businesses during an economic downturn is the exact right time to do it because it gives you runway. It's harder to raise capital, but if you can do it, it gives you an advantage.”
On top of those economic challenges, there was some initial resistance to the core concept of LinkedIn. When the site launched in 2003, Friendster defined online social networking, and Guericke says the common reaction to LinkedIn was something like, “Teenagers friending each other and trading pictures on social networks—sure! You want grownup professionals to friend each other over the web? This is too cute. Won’t work.” People also felt they lacked the first-mover advantage: “Even if it does work, Friendster will just add a business section to the site and you’ll be dead.”
Not only that, but as we’ve already mentioned, user acquisition was initially slow. Despite these challenges, LinkedIn stayed focused on growth. Echoing LinkedIn’s long-view approach, co-founder Allen Blue advised young companies, at a San Francisco growth hacker’s conference in early 2012, not to panic and lose focus when early growth is slower than anticipated. “Unless you have a really good reason,” he said, “Stick to your strategy.
Gaining Traction by Focusing in on the Tech Scene
One way that LinkedIn overcame these challenges and gained traction was by focusing first on the Silicon Valley tech scene. Upon launch, the founders invited the professional connections they’d amassed via their previous work in and around Silicon Valley. Hoffman says of LinkedIn’s launch, “We started slowly in the first few days because we wanted to make sure the systems worked. I think the 13 people associated with the company invited 112 people.” 
Former LinkedIn employee Keith Rabois explains that, in particular, Hoffman chose to invite successful friends and connections, “recognizing that cultivating an aspirational brand was crucial to drive mainstream adoption.”  Having the power players of Silicon Valley’s dot-com successes on the network quickly increased the appeal of LinkedIn, making it a must-have for up and coming Valley workers who wanted to connect with potential investors and advisors.
Quora contributor Jacque Swartz, who’s worked in and around Silicon Valley for forty years, was one of the first 100,000 LinkedIn members. He explains:
“[LinkedIn] was by far the best place to find knowledge and resources related to technology. The early responses to queries were astounding. We were a community and we took the time to help one another. At the scale when I joined, few were inundated with requests and nearly everyone actually did know their connections well.”
As more and more members of the tech community joined LinkedIn, the network effect took hold, and the site became the place to connect and access resources. It also made it easier to stay in touch with established connections, as before LinkedIn, frequent job changes common among startup talent in the Valley meant losing touch because of changing email addresses and phone numbers.
In many respects LinkedIn solved the classic chicken and egg problem of a network effect business by localizing the network to achieve critical mass around the Silicon Valley audience. Much like Facebook did five years later by constraining network growth to a single school, or Uber did a decade later by launching in one city at a time, LinkedIn kickstarted their network effects by tapping into a local population where it could reach critical mass.
This critical mass creates the utility needed in network businesses to create the high-quality must-have experience that breeds both user loyalty and word of mouth. By tapping local business heroes, LinkedIn was able to spark growth and make it a must-have network for Valley employees. From there it spread outward through the connections of the people on the platform.
According to some sources, LinkedIn kicked off their monetization efforts with Adbrite ads in mid-2004. The returns on these ads were insignificant, however, and it wasn’t until 2005 that LinkedIn launched three more lucrative revenue streams: job listings, subscriptions, and advertisements. It’s no coincidence that they achieved profitability in 2006. Guericke says of LinkedIn’s subscription model:
“The one thing that I feel is important, and it's probably not a good objective business decision, but I think as an entrepreneur I find it much more satisfying if I know certain users pay for my product. I feel like I've really created something of value. If all I create [is] something lots of people look at, and then advertise—let's say I have a social network site and it's all free but Gap sells t- shirts on it—it basically means Gap can figure out how to get money from these users, but I as an entrepreneur can't. It's kind of depressing, isn't it?”
Hoffman confirms that LinkedIn hadn’t originally considered doing advertising, but goes on to explain:
“Two things persuaded me to launch advertising as well. One of them was that our demographic was so good. The second one was that we began to realize we could build unique business products.”
Thus, rather than relying exclusively on ad revenue, LinkedIn has used ads in conjunction with other revenue streams, such as the freemium subscription model, quite successfully. Hoffman says:
“We figured [subscriptions] would help us get to profitability fast: We launched subscriptions, which was enhanced communications and search capability. People need to talk to people they don't already know in order to get the job done. That's the plural majority of our business today.”
Thus, LinkedIn monetized it’s key asset, offering subscriptions as a way to make connecting with others easier. It’s still free to sign up for LinkedIn and use the site’s most basic features such as creating a profile and connecting with professional contacts through referrals. However, LinkedIn Premium—which offers special packages for businesses, recruiters, job seekers, and sales professionals—boasts increased functionality and advanced features that vary from package to package.
Among other things, standard LinkedIn Premium can contact people outside their networks via InMail messaging; the Sales Professionals package boasts access to full profiles for everyone in users 1st, 2nd, and 3rd degree networks; Job Seekers are given top-of-the-pile status for the resumes; and Recruiters get a specially-designed workflow and search functions.
Though complicated, this tiered subscription system ensures that the many different types of users that engage with LinkedIn have a Premium package tailored to their specific needs at a price point that makes it affordable.
The most basic LinkedIn Premium packages—“Business,” “Job Seeker Basic,” and “Sales Basic”—are less than $20 a month (Sales Basic is just $16/month), billed annually. The biggest package, “Recruiter Corporate,” runs $719.95 a month.
The Value of Active Users - “It’s Easier to Focus on a Strength than Improve a Weakness.”
At a 2012 Growth Hacker’s Conference, LinkedIn’s Elliot Shmukler gave a talk on “Lessons Learned While Growing LinkedIn from 13 to 175 Million Users.” According to Shmukler, LinkedIn learned that “it’s easier to focus on a strength than improve a weakness.” Shmukler provided the following numbers, representing the growth channels that LinkedIn focused on improving in 2008: email invites and sign-ups from homepage views.
Email Invitations: 4% 25.000 -> 7% 44.000 (+19.000) took 2 years Homepage Views: 40% 50.000 -> 50% 63.000 (+13.000) took 4 months
Driving 40% of signups, the LinkedIn homepage was already a clear strength for the company, whereas email invitations, accounting for just 4%, were a clear weakness.
Their data indicated that people who arrived at the site organically visited, on average, thirty pages per session, while people coming through an invite visited, on average, just ten pages per session. They drew the conclusion that invites were not attracting highly engaged visitors, and therefore not a channel that would be a big success regardless of how they grew it. In other words, email invites were not one of their strengths when it came to driving growth.
Understanding that LinkedIn was already doing a good job with users arriving to the homepage organically, they chose to double down on this group—since they were already the more engaged segment—by removing as much friction as possible from their user experience.
This was clearly a smart move on LinkedIn’s part. LinkedIn was able to grow in four months almost the same number of signups from homepage improvements as they did over two years of email invite optimizations. Of course a near doubling of the effectiveness of email invites is nothing to look down your nose at; but these numbers do indicate that when looking for big gains in a relatively small timeframe, focusing on improving strengths presents a more powerful opportunity for growth.
Another example of playing up strengths comes from LinkedIn’s “Who’s Looked at Your Profile” emails. The emails had a 5% click-through rate (CTR) for inactive users, but a 20% CTR for active users. Rather than trying to woo inactive users, LinkedIn chose to once again focus on their strengths, making the emails more appealing to active users by testing subject lines, copy, and formatting. Shmukler sums up the core concept behind this, explaining, “It is easier to get an active user to do a lot more than to get an inactive user to do anything.”
Growth First: Virality
But the value of active users isn’t just in their engagement—active users also play a critical role in both re-activating inactive users and bringing in new ones, making virality one of the biggest keys to LinkedIn’s growth.
It’s easy to understand why. A network of professional contacts is only as valuable as the richness of the results when you’re searching for a connection. In order to make LinkedIn the de facto professional network Hoffman knew they needed to get as many people on the site as possible.
Hoffman claims, “2003 was all about tuning and viral growth.” He continues:
“We had this initial challenge of, ‘How do you get a million people?’ The first challenge was getting enough people so that functions like searching for people or sharing information had enough people in it to be valuable.” 
Early employee Josh Elman credits the Double Viral Loop for LinkedIn’s early growth. This virality wasn’t arrived at by accident, but actively tweaked, tested, and encouraged. As former LinkedIn employee Keith Rabois echoed this sentiment on Quora, explaining, “LinkedIn also intentionally deferred any features related to revenue or engagement until after the growth path was established, which took nearly 1.5 years.” 
So what exactly did they do to encourage this virality? The more apt question might be, what didn’t they do?
For starters, they tested everything. From the number of friends new users were asked to invite to the invitation messaging, the company worked to find the winning combination that converted the most invites to new users. For example, they found that four was the magic number of default email fields for the invites page—any less, and people simply skipped over them; any more, and people got overwhelmed. Similarly, the seemingly “throwaway” line at the end of the LinkedIn invitation copy below was shown to result in more invites sent by new users:
“So I found you while I was looking around the network. Let’s connect directly, I’m happy to help you with requests and forward things incoming. It will probably make both of our networks bigger.”
Elman refers to this as inception, or planting the idea of why your product is going to be useful or meaningful to users before they ever even sign up. As Elman explains, these combined efforts led to a decent but slow level of virality, or a single viral k factor.
The vast majority of users had a single connection—meaning they had accepted an invitation but not gone through the steps to connect with or invite anyone else. Less than 25% of new users actually went through the process of typing in email addresses to invite new users.
It’s at this point that LinkedIn began dabbling in the concept of contact importing, something that’s commonplace now but was pretty novel in 2004. At this point in time, the concept of typing in your email and password and letting a website sift through your contacts was new and furthermore most people didn’t even have contacts in their webmail clients.
To account for these challenges, LinkedIn built an Outlook plugin that could be installed and mined a user’s Outlook contacts for them. Though the process was certainly laborious by today’s standards, it was still a vast improvement over manual entry. As many as 7% of users uploaded their address books, and the number of invitations sent increased by more than 30%.
Though virality was certainly on an upswing, most users still had just one connection, and it took receiving 3.2 emails on average before a person would actually register for LinkedIn. It was at this point that LinkedIn decided to leverage what information they did have an excess of—current position.
When people signed up for LinkedIn they were asked about their current company and title, and over 90% of people answered this question. This information was used to engineer what Elman calls the Reconnect Flow.
With the Reconnect Flow, once new users signed up, they were immediately presented with a list of people at their current company already on LinkedIn and the question, “Who do you know?” Connecting was as simple as going through and checking boxes.
After a bit of success from this feature, LinkedIn went back in and added another question into the new user flow, this time asking where they used to work. Again, new users were presented with another list of potential connections from their former companies.
The genius behind the Reconnect Flow is that it not only allowed users to connect with contacts, but it also built out the new user’s profile—every piece of information entered was listed as part of their work experience. Furthermore, as more people joined and sent invitations to connect, current (though perhaps unengaged) users were brought back to the site—at which point they too were prompted to invite and connect with others.
These efforts combined to increase LinkedIn’s virality in a big way. Pageviews increased 41%, searches increased 33%, and there were 38% more positions listed on profiles. And despite the fact that the invitation function was moved to a much later point in the new user flow, invitations still increased by 16% as well.
The process above is what Elman cites as giving LinkedIn the Double Viral Loop. New users invite more new users and also engage old users (who go on to invite new users themselves.) Two viral loops happening at once—brilliant. 
Though this relentless testing and tweaking of flows helped LinkedIn to establish viral growth, they haven’t stopped improving the registration and invitation process. For starters, the aforementioned Address Book Uploader has also been simplified and streamlined as more and more people have switched exclusively to webmail.
The Endorsements feature, which debuted in September 2012, is yet another way that new and active users can reactivate their unengaged connections. Though people question its value to users, for LinkedIn it’s a boon. When compared to costlier solutions like paid ads and email campaigns, relying on virality to re-engage inactive users is both less expensive than paid ads and far more effective than reactivation emails from the company.
In 2006, the same year that LinkedIn introduced Recommendations and People You May Know, the company debuted one of its most talked-about growth hacks—public profiles. Much like the Address Book Uploader, this seems commonplace now, yet before LinkedIn made user profiles public, it was exceedingly unlikely for real people to show up in organic search results.
Making profiles public created big traffic and acquisition gains for LinkedIn. Profiles showing up in search results put LinkedIn in front of more and more people. Plus, once people clicked into the site from search, they had to then sign up for LinkedIn before they could connect with the person they were searching for.
Not only that, but public LinkedIn profiles made having LinkedIn that much more desirable for users who were hoping to up their profile. The site’s natural weight in Google results put user profiles quickly at the top of results for name-based searches in Google. In addition to connecting with people via the site, they could reach people who didn’t even use the site thanks to search.
The key to pulling this off, however, was gaining enough initial growth for public profiles to actually make an impact, which is why the company waited until they’d reached 2 million users before they began indexing user profiles. 
Due to privacy concerns, the company faced some criticism for making this move, and LinkedIn made it possible for users to hide their profile from Google search or limit the amount of information available on their public profile—the view seen by people who aren’t connected to a user.
Hoffman explains, “I'm a huge believer in getting a million people, getting them engaged, and then building a business model on top of that. I knew I wasn't planning on really trying to work on a business model until later.” 
Indeed, one of the driving forces behind LinkedIn’s growth has been the company’s ability to realistically assess what’s working and what isn’t, and to adjust their approach accordingly. For example, the site’s early privacy controls severely impacted the usability of the site by making it impossible for users to see how many degrees separated them from someone they wanted to connect with—after all, an introduction via a common acquaintance is much more likely than an introduction that requires five or six people. Within months of their launch, LinkedIn resolved this issue by making degrees of separation visible.
Another way the company improved the site’s usability early on involved improving the search function. The company’s original assumption was that LinkedIn would be used primarily to search for and make new connections, so it was possible to search for things like titles and skills, but not names.
Yet, as it turned out, people wanted to use LinkedIn to make new acquaintances and keep in touch with established ones, so the company modified the site’s search function to work with names.
LinkedIn also launched the Address Book Uploader, which allowed users to see which of their contacts were already on LinkedIn, as well as invite those who weren’t. The Address Book Uploader had a twofold advantage: not only did it improve the site’s user experience, but it increased signups via referrals sent by users. Guericke explains:
“I think it's key to learn very quickly what you missed. But not just to do what the user asked, which would have been the name search, but to say like, okay, ... now we want to do the address book upload and show you right away these are your contacts who are already on LinkedIn.”
Rather than merely adjusting the search function to include names, the addition of the Address Book Uploader immediately solved the problem that new users were trying to solve for in a way that they didn’t know to ask for.
Today’s Growth Engine
Of 2012, A Brief History of LinkedIn says:
“Project Inversion and a completely re-architected site enabled an unprecedented pace of product innovation and transformation — of the site and the company, which focused on three concepts: simplify, grow, everyday.”
The company’s activities that year (and the one that followed) definitely embody those three concepts. In February of 2012, LinkedIn acquired the Gmail plugin Rapportive, which lets users connect with their contacts on LinkedIn right from Gmail and displays their most recent social networking updates, for $15M cash. This extended the ability to build LinkedIn connections from the site to user’s primary online productivity tool—email.
Just three months later, in May of 2012, LinkedIn acquired SlideShare, a platform for sharing professional content like presentations and business documents, for $119M. In the press release announcing the acquisition, LinkedIn CEO Jeff Weiner said:
“Presentations are one of the main ways in which professionals capture and share their experiences and knowledge, which in turn helps shape their professional identity. … These presentations also enable professionals to discover new connections and gain the insights they need to become more productive and successful in their careers, aligning perfectly with LinkedIn’s mission and helping us deliver even more value for our members.”
With more than 9 million presentations and around 29 million monthly uniques at the time of acquisition, SlideShare represented real growth for LinkedIn. Less than a year later, in March of 2013, LinkedIn acquired popular news reader Pulse for $90M, claiming their goal was to make LinkedIn:
“the definitive professional publishing platform – where all professionals come to consume content and where publishers come to share their content. Millions of professionals are already starting their day on LinkedIn to glean the professional insights and knowledge they need to make them great at their jobs.” 
This acquisition in particular fulfills the third concept mentioned in A Brief History of LinkedIn—everyday. When looked at as a whole, these three acquisitions—Rapportive, SlideShare, and Pulse—are part of a larger effort on LinkedIn’s part to become more than a site where people go to find jobs and hire people.
Perhaps the most significant concept is everyday, and this seems to be the biggest of the driving forces behind LinkedIn’s future growth engine, even as the aforementioned forces—in particular, subscriptions and virality—continue to play a major role.
Launched in 2011, one of the company’s biggest nods toward the concept of everyday is LinkedIn Today—which offered users a way to “cut through the clutter” and stay in-the-know without having to juggle multiple websites, blogs, tweets, and newsletters. 
LinkedIn today worked by culling news from the articles that a user’s coworkers and connections are sharing, those their industry peers are sharing, and those that are gaining attention across other industries. Users also have the option of following industries outside their own that they may be interested in or affected by.
The service also allowed users to see what their connections were reading and who had originally shared the articles featured in LinkedIn today. There was also a social component to the service; in addition to merely reading articles, users could share and comment on them as well. Along with the desktop component, LinkedIn Today launched as part of the LinkedIn iPhone app, allowing users to read and save articles on the go. 
Though LinkedIn Today still exists as a separate entity at http://linkedin.com/today, the feature is now handled via Pulse, and it has been somewhat integrated with the news feed on each LinkedIn user’s homepage.
One of the biggest limitations of LinkedIn Today was that is was merely a news aggregator. Though engaging and convenient, there was no original content. For this reason, LinkedIn launched their Influencer program in October 2012. The idea was simple—select “thought leaders” to create and share content directly with users, exclusively on LinkedIn.
Influencers include the likes of Richard Branson, Jack Welch, and Arianna Huffington, and users can follow these thought leaders without being connected to them. As with earlier LinkedIn Today content, these articles can be read, liked, shared, and commented on within LinkedIn.
With hundreds of Influencers as of this article’s publication, the program has been hugely successful for LinkedIn. On average, an Influencer post receives close to 30,000 views, with some receiving more than a million and as many as 2 million. We’ve already touched on LinkedIn’s diverse user base, and that diversity is reflected in the Influencer audience as well—22% of Influencer followers are entry-level professionals, and 49% are director-level or above—for which Hubspot co-founder and LinkedIn Influencer Dharmesh Shah credits the diversity of the Influencers themselves. 
Shah explains that while most media sites must narrow their focus to a specific audience, this isn’t the case with LinkedIn. He goes on to claim:
“The customizable nature of LinkedIn Today – due to the ability of users to follow selected Influencers as well as to focus on specific topics, industries, etc – means that LinkedIn Today can be (almost) all things to all people, because every person gets to decide ‘what’ his or her LinkedIn Today delivers.” 
Shah goes on to refer to the Influencer program as “one of the smartest inbound marketing campaigns I’ve ever seen”—which means quite a bit coming from the guy who literally wrote the book on inbound marketing and helps run the inbound marketing powerhouse HubSpot. Shah, the sixth most popular Influencer at the time, explains that in less than a year of writing as an Influencer, his posts generated 3.7 million views for LinkedIn; the top three Influencers together had generated 18.8 million views.
The key is that Influencers program isn’t just good for LinkedIn—it’s good for the Influencers themselves, which is why they’re so willing to spend their limited time creating content for the site. Shah explains that, in contrast to his popular personal blog, where posts get on average 5,000 to 10,000 views, his Influencer posts on average garner 123,000.
Through smart acquisitions and features such as LinkedIn Today and Influencers, the site is quickly becoming the everyday destination they want it to be.
Mobile has been a huge driver for the company, and LinkedIn has kept pace with general mobile adoption through a series of apps, mobile sites and products designed for the mobile user experience.
As Jeff Redfern, VP of mobile product at LinkedIn, puts it, “We’re becoming a mobile company. We’re going through this metamorphosis. We started as a caterpillar and we’re going to exit this as a butterfly.” As of February of this year, a full 41% of LinkedIn traffic was coming from mobile—up from 38% the previous October. 
Here’s how they’ve managed that change.
In early 2008, LinkedIn launched an iPhone-optimized mobile site at m.linkedin.com. Complete with international versions in French, German, Spanish, Japanese, and Chinese, this beta site included basic LinkedIn features like profile search, contact research, invitations, and network updates, along with promises for expanded features like LinkedIn Answers and LinkedIn Experts in the near future. 
In 2011, the company retooled the mobile user experience on both native Apple and Android apps, along with a new HTML5 mobile site. They explained via the LinkedIn blog, “LinkedIn Mobile page views have grown more than 400% year-over-year, making it the fastest growing consumer service on LinkedIn.”  The new mobile apps were redesigned around what had become their most popular mobile features—updates from connections and LinkedIn Today; the inMail inbox; each user’s own profile and updates; and groups.
Then in October 2013, LinkedIn announced the launch of a new app called LinkedIn Intro, which leveraged the technology acquired with Rapportive earlier the previous year. In many ways, LinkedIn Intro was pretty groundbreaking—an app designed to bring the power of LinkedIn, and the technology of Rapportive, straight to the iPhone’s Apple Mail app. Users were able to see LinkedIn profiles in the iPhone Mail app.
For example, when an Intro user receives an email from someone they don’t know, the users sees more than just an unrecognized email address—they also see a snippet of that person’s LinkedIn profile, complete with photo, company, and position. Tapping on the snippet provided more information—location, education history, mutual connections, past and current occupations, and of course the ability to connect on LinkedIn. 
Just four months later, in February 2014, in a blog post titled “Doing Fewer Things Better,” the company announced they were shutting down Intro, along with Slidecast and support for certain versions of the LinkedIn mobile app. Nevertheless, many speculate that the end of Intro had more to do with security concerns than anything else, as Intro worked by routing emails through LinkedIn's servers, scanning them for certain types of content, and temporarily storing users’ email account passwords. 
Despite the Intro hiccup, LinkedIn has cultivated a thriving and multi-pronged mobile web presence, with not one but four mobile apps—LinkedIn Phone, LinkedIn iPad, Contacts, and Pulse. While the first two are fairly straightforward apps, Contacts and Pulse serve as a bit more of an extension of the site’s current functionality.
Contacts not only stores contact information, but it provides job change and birthday alerts and stores relationship history that is, in the company’s own words, “available at moment’s (or a meeting’s) notice.” The Pulse app, by contrast, is yet another extension of LinkedIn’s shift toward everyday, allowing users to choose from thousands of sources to create a custom news feed, explore trending content, and share with their networks.
The LinkedIn Growth Story
The LinkedIn growth story is an instructive one, because it provides us with a look at a very successful company from start to public offering. It’s clear that LinkedIn understands and values growth on all levels and is willing to experiment with a variety of growth strategies to find what ultimately makes the platform as valuable to as many users as possible.
With the growth in mobile, acquisitions, and content, LinkedIn has continued to evolve from its original mission but has kept the primary value of the experience intact, something that is not easy to achieve. As LinkedIn continues to grow, their need for finding new upside at scale will continue to push them to innovate, acquire and rethink how users use LinkedIn. As more mobile-first millennials come into the workforce, LinkedIn will be tasked with addressing the needs of a changing workforce to remain relevant and growing.
There’s a lot to cover in the 12 years since Reid Hoffman began building LinkedIn. What did we miss? What key factors would you add to the LinkedIn growth engine? And what’s next for them?