social networking
n. Using a website to connect with people who share similar personal or professional interests, particularly where the people in the site's database are connected to each other as friends, friends of friends, and so on.
Other Forms
Examples
2003
To attract users, Currier's matchmaking company, Tickle Inc., recently incorporated a software feature called social networking into its website. The six-degrees-of-separation software links people through their mutual business or personal connections, allowing them to mine their friends (and their friends' friends) for sales leads, job-hunting tips, friendship, or dates.

The digerati are anointing social networks, of which Friendster is the early leader with more than 4 million registered members, with lofty monikers like "Internet 2.0" and "the people web." If the Internet's first stage, they say, was about publishing what people know, this next stage is about exploiting who people know.
—Chris Gaither, “Six Degrees Co.,” The Boston Globe, December 07, 2003
2003
In the free-ranging world of the Internet, the ties created by social-networking sites have people excited. Some are calling it a social revolution. Much of the talk has focused on how well sites like Friendster aid dating. But social networking can be used for lots of other things—for example, at a later stage in life, finding a babysitter. You might find someone to play tennis with, or someone who likes the same kind of music you do and can suggest new artists. And if the best jobs come through connections, what better way to find work than through a giant online social network? In San Francisco, where unemployment is rampant and social networking is nearly an obsession for just about everyone under 35, it seems everybody looking for a job is using sites like Friendster, Linkedin, Tribe.net, or Ryze, all of which allow you to join only if you invite friends to join with you, or if you are yourself an invitee.
—David Kirkpatrick, “I Get By With A Little Help From My Friends Of Friends Of Friends,” Fortune, October 13, 2003
2003
Given the right knowledge of the people between us, I could probably plot a chain of people between myself — here in the depths of the Swedish countryside — and you, wherever you are. If such information was available, and it turned out it might be advantageous for us to chat, then we could ask each of the middlemen in turn for an introduction and get on with it. Or we could skip the middle guys altogether. That's the idea of the growing number of social network sites on the net today.
—Ben Hammersley, “Social networks: Click to the clique,” The Guardian, January 09, 2003
1998 (earliest)
Venture capitalists ponied up money for…a provider of Internet-based social networking services
—Ronald Rosenberg, “Software,” Boston Globe, May 24, 1998 (OED)
Notes
The non-digital form of social networking — using a network of people to exchange information, enhance job prospects, or otherwise further one's career — began in the mid-70s (the earliest use of the phrase social network dates to 1976). It reached full flower during the go-go 80s, those heady quid-pro-quo, win-friends-and-influence-cocktail-party-people days. By the mid-90s, however, this form of networking faded from view, encrusted as it was in a thick layer of irony and comedians' jokes.

That's not to say that the idea and practice of networking no longer existed; "It's not what you know, it's who you know" remained the received (if rather cliched) wisdom. It's just that social networking ceded the spotlight to computer networking, first in the local sense of hooking up nearby computers, and then in the broader sense of the Internet and its overused "network of networks" definition.

And that has now brought us full circle with the Internet updating and improving upon the idea of social networking. Millions of people have registered with sites such as Friendster.com and Match.com. In most cases you can only sign up if you're invited by a friend or colleague who is already registered. Each new member is asked to provide a profile of who they are: their interests, hobbies, skills, professional affiliations, and so on. The other members can search on these profiles and use the results to contact people who might be able to help them out. Nowadays, it's not what you know, it's who you can find online.