Buy in in poker depends on the playing table and is the minimum number of chips a player must buy for the right to play. This can also mean the amount of the entry fee for a poker tournament (which will be a number of chips).
Number of chips for a buy in
The number of tokens varies on tables and tournaments and is selected based on the value of the blind and the style of game to be played. When the buy in contains about 20 times more tokens than the value of the big blind is called a small buy in promoting aggressive behavior where players lose their chips faster, on average. When the buy in contains about 50 times (or more) tokens than the value of the big blind is called deep buy in, encouraging cautious behavior of players (eg promoting long games in tournaments).
Right to rebuy
Rebuy is a term often used in poker on the internet and in real life, to define the ability of a player who lost his initial buy in, to return to the game table with a new amount (often the same as the first time ). To sit at the table again the player will have to pay a second time. In principle, during the poker tournaments there can be no rebuy as the game proceeds by successive elimination of the players.