Steam Trading Cards

[Tiger]

Just seems like a way to get idiots to spend all of their money on useless shit to me.

B-but...You get them for playing... ._.

Free to play games drop game cards based on your in-game purchasing. For every $9 USD spent (approximate) since the start of the Steam Trading Card Beta, you will earn one card drop. This card will drop at some point as you play. If you have made in-game purchases in Dota 2 or Team Fortress 2 prior to the Steam Trading Card Beta, or if you owned Team Fortress 2 prior to the Free to Play update, you will have 4 or 5 additional card drops available.

So, yeah. You buy games to get cards, and for free to play games you buy useless items to get cards. Either way, Steam makes a shitload of money for something which is literally of no use whatsoever. I don't know why so many people buy into this microtransaction shit, but it's all jive in my opinion.

Did you even read the page Corinthian linked?

What do I get when I craft a badge from my Trading Cards?
In addition to getting the Game Badge itself, you'll get:

a random emoticon item created for this game, that can use in chat or discussions;
a random profile background item created for this game, that can use on your Steam Community profile
a chance to get a discount coupon for a different game or DLC
100XP, which may increase your Steam Level