I recently bought Terraria and have been receiving these "Steam Trading cards" while playing. I don't have any knowledge on them but I enjoy collecting items, so I'm intrigued; What are they, exactly? How do I get more? How do I trade them?
All the items in my inventory are 'Common' – does that mean there are rarer ones? How do you get those?
Best Answer
Steam Trading cards
When you play certain games on Steam, you can earn 'Trading Cards' as a collectible item. Those cards are placed into your Steam inventory.
If you collect a full 'set' of cards for a particular game, you can trade that set in for items for your profile, as well as a 'completion' badge. The items you can earn are as follows:
Games might have different 'levels' of card sets, requiring you to collect the same set multiple times to fully max out your badge or earn more items.
Most games will drop half the total amount of cards. For example, Half-Life 2 has 8 cards in a set, so you will receive (max) 4 card drops. You can check how many drops you have remaining on your badges page. This basically means you won't be able to complete sets based purely on drops. This is where the Steam community steps in.
Completing sets
There are a couple of ways to build complete sets
A good place to look for potential traders, is in the Steam community - especially forums and groups for that particular game. Another option is dedicated 'Steam Trading Card' groups, both on and off Steam.
You can read more about Steam Trading Cards on Steam's FAQ