Royal Straight Flush This is the highest hand possible in a natural game, and it does not use any wild cards. It consists of the Ace-King-Queen-Jack-10 all of the same suit.
Straight Flush This is the second ranking hand its similar to the royal straight flush, however you can use any five cards of one suit that are in a row. For example the 2 of Spades through the 6 of spades would be a straight flush.
Four of a Kind The next highest ranking is four of one card. Four aces would be the best in this ranking sequence, going downward to four 2's being the lowest.
Full House Often referred to as the boat its made up of one three of a kind and one pair. Three Aces with a pair of Kings is the highest possible full house. If you had three Queens and a pair of 6's it would be declared as Queens over 6's. Full houses always list the three of a kind prior to the pair.
Flush A flush consists of any five cards that are of the same suit. These cards do not have to be in a row to qualify as a flush, they only have to be of the same suit. For instance, a 2-Jack-6-9-Ace of spades would be a flush.
Straight This hand is made by five cards, which are in a row numerically. The cards do not need to be of the same suit. The highest achievable straight is Ace-King-Queen-Jack-10.
Three of a Kind Often called Trips, because of the triple use of a card. This hand consists of any three cards, which are of the same numerical value but not of the same suit. A hand with three aces is the highest set of trips.
Two Pairs This is a hand consisting of two sets of two cards each, which match numerically. For example 10-10-8-8.
One Pair The second lowest ranking hand you could possibly get is a single pair. This hand is made up of two cards, which are of the same numerical value.
High Card In some instances the winning hand may be determined by the rank of a single card. The highest card is the Ace. If more than one person is holding an Ace the second highest card would decide the winner ...  then the third card etc.