Board Thread:General Discussion/@comment-70.72.28.7-20150205045944

I keep seeing these sort of items I get for buying a game, or playing a game on steam. I can turn them into gems, and once I have enough gems, I can convert them into a booster pack.

What is that for? What can I do with it? I can find lots of threads explaining how to get one and so on, but nothing about what it actually is. 