There are 52 cards in a standard pack of playing cards. The Ace is the highest card going down in value to the Two and all the suits are equal. A Poker hand consists of five cards and the ranking of these hands is as follows from best to worst
Royal Flush
A straight from a ten to an ace and all five cards of the same suit. In poker, suits do not matter and pots are split between equally strong hands. The chances of getting a Royal Flush are approximately 1:240,000 !
Straight Flush
Any straight with all five cards of the same suit. Our example shows a 9-high Straight Flush.
4 of a Kind
Any four cards of the same rank. If two players share the same Four of a Kind, the fifth card (kicker) will decide who wins the pot, the bigger kicker the better. Our example shows 4 of a kind in Aces with a Jack kicker.
Full House
Any three cards of the same rank together with any two cards of the same rank. Our example show "Aces full of Jacks" and it is a bigger full house than "Kings full of Aces".
Flush
Any five cards of the same suit which are not consecutive. The highest card of the five makes out the rank of the flush. Our example show an Ace-high flush.
Straight
Any five consecutive cards of different suits. Our example show a Ten-high straight. When comparing two straights, the one with the higher ranking top card is better. Ace can count high or low in a straight, but not both at once, so A-K-Q-J-10 and 5-4-3-2-A are valid straights, but 2-A-K-Q-J is not.
3 of a Kind
Any three cards of the same rank. This combination is also known as Triplets, Trips or a Set. If you have to compare two 3 of a kind hands, then the higher of the two remaining cards in each hand are compared, and if those are equal, the lower odd card is compared. Our example show three of a kind in Aces with 8 & 2 as the kickers.
2 Pairs
Any two cards of the same rank together with another two cards of the same rank. Our example show two-pairs, Aces and Eights with a 10 kicker.
1 Pair
A hand with two cards of equal rank and three other cards which do not match these or each other. When comparing two such hands, the hand with the higher pair is better. If the pairs are equal, compare the highest ranking odd cards from each hand; if these are equal compare the second highest odd card, and if these are equal too compare the lowest odd cards.
High-Card
Five cards which do not form any of the combinations listed above. When comparing two such hands, the one with the better highest card wins. If the highest cards are equal the second cards are compared; if they are equal too the third cards are compared, and so on. So A-J-9-5-3 beats A-10-9-6-4 because the jack beats the ten.