poker
Poker is a family of comparing card games in which players wager over which hand is best according to that specific game's rules. It is played worldwide, however in some places the rules may vary. While the earliest known form of the game w ...
and gaming "buying in" is the process of entering a
tournament
A tournament is a competition involving at least three competitors, all participating in a sport or game. More specifically, the term may be used in either of two overlapping senses:
# One or more competitions held at a single venue and concentr ...
that requires an up-front payment. The size of the payment, otherwise known as the "buy in", determines the total winning prize pool and also contains a fee, otherwise known as the rake, that is paid to the house.
For example, a 50-person capacity tournament could cost $55 entry per player. In poker terms, this could be presented as "$50+$5", meaning $50 goes to the prize pool to pay the eventual winners and $5 (10%) is the rake. In this example, the prize pool would contain $2500 and the house would take a total of $250 (i.e. 10%).