When playing backgammon for money, (whether or not in an online backgammon room), the backgammon game is usually played on an agreed upon stake per each game until a certain score is reached or one of the players resigns from the game.
Even when the initial stake is small, a backgammon game for money can end up as a high stake game due to the doubling cube, gammons and backgammons.

Doubling Cube

The purpose of the doubling cube (a special backgammon die, which its six sides are marked with 2, 4, 8, 16, 32 and 64) is to increase the action in the backgammon game, especially when backgammon is played for money. According to backgammon rules, a player can suggest at the beginning of his turn to use the doubling cube.

If the opponent agrees to use the doubling cube, then the initial stake will be doubled. For example, if it was agreed to play backgammon for $5 per match, the backgammon game will now be played for $10 per game.

The doubling cube enters the game only if the opponent agrees. If refuses, he must forfeit the game and pay his opponent the initial stake. If agreed, the opponent becomes the holder of the doubling cube and he may suggest redoubling, i.e. play backgammon for $20 a game.

Gammon

When the opponent of the backgammon winner hasn't borne off any of his checkers, the game ends up in a gammon. In this case, the losing player pays the winner double the value appears on the doubling cube.

Backgammon

Backgammon is a situation when the game is over with the losing player not only hasn't borne off any of his checker, but also left some checkers on the bar/the opponent's home board. When playing backgammon for money, the winner receives triple the value shown on the doubling cube.