Basically, it's digital distribution. You download the steam client, and get an account. Then buy games associated with the account (pretty much anything you could want is on steam these days) and then it goes into your purchased game library. Steam has all sorts of deals running (this week it's like 50% off a bunch of stuff). And you can download/install them on any machine through the steam client. Keeps track of all the updates for you. Some games you can put your saves on the cloud, so when you install on a new machine it keeps your saves.
Good Ole Games is another great website. Especially for some older games that you might be familiar with, for a pretty fair price.
I never understood the whole "gamer" phenomenon. Explain? Is it your alter ego in a parallel life?
A friend here at work plays. His wife hates it. He comes into work with obvious signs of no sleep. He's an addict.
Just like any other hobby or activity there are people who get to involved in it. A lot of video gaming I do involves games with indepth stories that will rival any novel out there, or games that provide social aspects. Multiplayer games that I get to play with all the friends I have scattered around the world. I can't hang out with them, so I might as well sit down for an evening playing some silly FPS and drinking a few beers while we bullshit and just have fun.
I fired my account up last night, anyone still running around? I know a couple members were playing last year.