A ring game, also called a cash game, is a regular poker game played for table stakes. It is so named because typically the players are sitting around an oval table in a ring. Originally, ring games meant games played for cash, but with the advent of free online poker rooms, it can also mean playing for "play money" instead of cash.
Ring games may be of any form of poker; the term does not indicate any particular variant.
You may also hear of side games, which are simply cash/ring games played at tournament venues (usually "on the side" of the tournament, hence the name... side games are often populated by players who have just gotten busted out of the tournament).
The alternative to a ring game is a tournament.
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