Just before we proceed, surely the question as to the exact nature of Steam Trading Cards need to be answered. In any case, individual games will have a set of cards, where half of each set can be unlocked as long as you play the game, while the other half is earned via what Valve has dubbed “collecting prowess”, and if you were to read between the lines, trading with your friends would play a huge role in this matter. Whenever you have a full set of cards, just exchange them for a game badge which will help you earn stuff such as emoticons, profile backgrounds, and coupons. Collect the same set of cards over again to “level up” – spending real world time to obtain virtual achievements.