Steam Trading Cards are virtual cards earned by playing games on Steam that can be combined into game badges.

Play any of the participating Trading Cards games to get trading cards. Up to half the card set is dropped through game play, the other half is earned through your collecting prowess.
Once you've collected a set of cards you can craft them into a game badge. Like the current badges, they are tied to your account and are shown on your profile. Unlike the current badges, crafting games badges earns you tradable items like emoticons, profile backgrounds, and coupons. Level up your badge by collecting the set again and earning more items.
All badges now have XP which contributes to your Steam Level, a summary of your badge collection. You can view someone's Steam Level by hovering over their avatar. Leveling up earns you non-tradable items like profile showcases, extra friends list slots, and more.
You will never be banned for trading in this group!

Visit the update page for more details.

Participating Games[http//steam]
Trading Cards Overview[http//steam]
Frequently Asked Questions[http//steam]