My history of social networking is fairly uneventful, I've never really got into it in a big way, but I've enjoyed dabbling with it.
I signed up to MySpace years ago, and soon got bored of it. Then I joined Facebook. Which would be brilliant if it wasn't so saturated with spammy apps.
The "biggest thing" at the moment seems to be Twitter, which oddly is also the smallest thing in terms of what it does - just short messages, of no more than 140 characters (although they can include hyperlinks). That's about it really. You can post to Twitter from your computer, or even from your phone (via SMS, or via mobile Internet).
You can view the latest messages posted by the entire Twitter community if you want (although you can choose for your own messages not to show in this bit), or you can view the recent messages from the people you've chosen to follow.
These can be your real life friends if you want, but it seems that most people use it to follow celebrities so that they can regularly receive important updates about the minutiae of their celebrity lives.
Some celebrities provide genuinely interesting updates about what they are up to, while others seem to have PR people running their Twitter accounts for them, which can make them a bit boring to follow.
Stephen Fry is one of the most popular people you can follow, and he treats his virtual stalkers with a near-constant stream of updates, wherever in the world he might happen to be. He is also known for interacting with his followers more than most.
On one occasion, he posted messages to Twitter (an act known as "tweeting", with the messages themselves being referred to as "tweets") from inside a lift he happened to get stuck in - he even posted pictures of himself and the other unfortunates during their incarceration:
In a way, it was as if all of us who Follow him were in there with him. Although not literally of course as 750,000+ people in a lift together for several hours would no doubt be somewhat unpleasant, even with Mr Fry present to provide his well-loved witty banter.
If you haven't already, come out and play with the Twitterers!