The winning hand is determined by seeing which hand has the strongest combination of cards, using any combination of "pocket" cards and "community" cards in Texas Hold'em, and a combination of 2 "pocket" cards and 3 "community" cards in Omaha and in Omaha Hi/Lo. The combinations are listed here from strongest to weakest hand.

A royal flush is an ace high straight flush.	A straight flush is a five-card straight, all in the same suit.
Quads, or four of a kind, are four cards of equal rank.	A full house, or full boat, contains a set (three) of cards of one rank and a pair of another rank.
A flush is any five cards, all of the same suit.	Five cards of sequential rank. Every possible straight will contain either a 5 or a 10.
Three cards of the same rank.	A two pair is two cards of one rank and another two cards of another rank.
One pair is two cards of the same rank.	The hand with the highest card(s) wins.