Buy-In
A buy-in is the amount of money you pay to enter a game or tournament.
The simple explanation
A buy-in is the amount of money you pay to enter a game or a tournament. In a tournament it is the entry fee that gives you your starting stack. In a cash game it is the money you bring to the table, for which you receive chips.
A closer look
Cash games usually have a minimum and a maximum buy-in, often between 20 and 100 big blinds. Players speak of stakes in buy-ins when they discuss bankroll management: a bankroll of 30 buy-ins means thirty times the amount you need to sit down. In tournaments the buy-in is divided into the prize pool and a fee, written as two numbers such as $100+$10. The term is also used as a verb: to buy in.
A practical example
A tournament has a $100 buy-in, so each player pays $100 to receive their starting chips.
Full explanation
A buy-in is the amount of money you pay to enter a game or tournament.
A buy-in is the amount of money a player pays to join a poker game or tournament. It is the initial investment that gives you your chips.
In a cash game you choose how much to buy in for, within the limits set by the room. In a tournament the buy-in is fixed and you receive an equal starting stack.
Buy-ins are also used as a unit of measure. Players say they won or lost ten buy-ins.
In tournaments, part of the buy-in goes to the prize pool and part to the organizer as a fee.
Alternative spelling: buy in, buyin