Low poker or lowball is not exactly a term but a variation of poker. The rules are quite similar to those of other variations of poker games with one major exception — the winner is the player who has the worst hand instead of the best one. It is like playing regular poker on Opposite Day. In other words, the royal flush is one of the worst hands you can get in low poker.
The best hand, however, depends on the variation of low poker you’re playing. There are several different variances of low poker, ace-to-five lowball (California lowball) and deuce-to-seven lowball (Kansas City lowball) being the most popular ones. In California Lowball the best hand is A-2-3-4-5, while the best hand in Kansas City lowball is 7-5-4-3-2 offsuit.