In the simplest way possible, a poker buy-in is the minimum amount of money you need to play a particular poker game.
In a tournament setting, the buy-in is an entry fee you have to pay to participate in the tournament.
For example, let’s say that you want to join in an online $2/$4 No-Limit Texas Hold’em poker game. In this case, the minimum required buy-in will likely be as little as $80, while the maximum allowed buy-in will be $400.
It’s widely accepted as good poker etiquette that you shouldn’t buy in with the bare minimum, especially if the players at the table have made significantly higher buy-ins.
The logic behind this is that everyone should ideally start with the same amount of money. To find out more, read our detailed article on the topic.