Happy 10th Birthday, LinkedIn!

Ten years ago today, LinkedIn was born. It’s radically changed my life over the past decade.

I had no knowledge of LinkedIn’s existence on the day it launched in 2003. But a few days later, I got an invitation from my former PayPal colleague Keith Rabois to join this new site, LinkedIn. I signed up (as user number 1400 or so), saw a few familiar names on it, and was immediately intrigued.

In the months to come, I used LinkedIn a handful of times, connecting to colleagues and meeting a couple of entrepreneurs who reached out to me for advice on fraud prevention.

In late 2003 or early 2004, my former PayPal colleague Lee Hower reached out to me to see if I “knew anyone” who might be interested in working on data-type problems for this company LinkedIn. Lee and I had lunch, and I learned that LinkedIn had built its network out to be a couple of hundred thousand users. This was pretty cool, and something I could certainly see working on.

A week or so later, I was sitting in a Mountain View conference room with Reid Hoffman — with whom I’d spoken exactly once when he was a PayPal exec — and Jean-Luc Vaillant, brainstorming cool stuff we could do with data.

Not long after that, in February 2004, Jean-Luc set me up with a Mac laptop, and I started delving into the data. For the next few months, I was essentially moonlighting at LinkedIn, coming into the office one or two days a week, while mostly still at PayPal.

When I found that I was consistently more excited to get out of bed on the LinkedIn days than on the PayPal days, I decided I would (after biking around France for a month!) join LinkedIn full-time.

Thus began my LinkedIn employment odyssey. I worked full-time at LinkedIn from October 2004 until January 2007, leading a small analytics team with two awesome hires, Jonathan Goldman and Shirley Xu.

I learned a ton at LinkedIn, worked on some interesting and important products, and got to collaborate with lots of great people I now consider friends (and of course, LinkedIn connections).

After I left, my team became the large, influential and highly-regarded (kudos to Jonathan and DJ Patil) Data Science team.

Though I was no longer employed at LinkedIn from 2007 on, the company has continued to play a crucial role in my life. The first two engineers we hired at Circle of Moms, Brian Leung and Louise Magno, came in through the same LinkedIn job post in 2008.

Looking back at the Inmails I’ve sent, I see a number of people I reached out to try to hire and now know well; in many cases we didn’t wind up working together, but they became friends and valuable connections.

LinkedIn has prepared me for meetings with hundreds and hundreds of people. I wish I still had database access so I could run the query to figure out just how many.

When I first started poking around LinkedIn in 2003, I had a couple dozen connections. I looked at the profiles of people like Lee and Reid, seeing well over 100 connections. I figured I was simply not the kind of person who’d ever amass that number of professional contacts.

Today, I have over 900 connections on LinkedIn; the vast majority of those are people I’d feel comfortable reaching out to for an important professional purpose. Part of that increase is a reflection of my evolution, but a lot of it is thanks to LinkedIn.

To Reid, Jean-Luc, Lee, Allen, Chris, Sarah, Matt, and the millions of others who have helped to build LinkedIn, thanks and happy birthday!

Mike Greenfield founded Bonafide, Circle of Moms, and Team Rankings, led LinkedIn's analytics team, and built much of PayPal's early fraud detection technology. Ping him at [first_name] at mikegreenfield.com.