List Of Poker Hands In Order:

Royal Flush
The highest possible straight flush. eg 10 J Q K A of all the same suit.

Straight Flush
A straight of all the same suit. eg 3 4 5 6 7 of all the same suit.

Four of a kind
Four cards of the same rank. eg Q Q Q Q J.

Full House
Three of a kind plus a pair. eg J J J 2 2 beats 9 9 9 A A.

Flush
Five cards of the same suit. eg 2 3 6 Q A of all the same suit.

Straight
Five cards in sequence. eg 4 5 6 7 8. K A 2 3 4 is NOT a straight.

Three of a kind
Three cards of the same rank. eg A A A J 6.

Two Pair
Two separate pairs. eg A A 2 2 3 beats K K Q Q J.

One Pair
A 5 card hand containing two cards of the same rank. eg K K Q 7 3

High card / Nothing
A 5 card hand which doesn't even contain a single pair. eg A K Q 3 2 beats A K J 10 9.

Other Terms:

Hole cards
The first 2 cards dealt to each player in a round of Texas Holdem.

The Board
The community cards lieing face up on the table which all players can see and use.

The Flop
The first 3 cards dealt out onto the board

The Turn
The 4th card to be dealt onto the table.

The River
The 5th and final card on the board.

The Pot
The money in the middle of the table that everyone wants to win

Go All In
Put all of your money into the pot.

Side Pot
If a player goes all in, then the pot which they can win must not get any larger. For other players to keep on betting they must put their chips into a Side Pot. If the All In Player has the best hand at Showdown then the second best hand will win the side pot. In big hands there can be multiple side pots.

Blinds
The chips put into the pot by the 2 players sat to the left of the dealer before the first cards are dealt.

Pocket Rockets / Big Sticks / American Airlines
A pair of aces in the hole. The best possible starting hand.

Cowboys
A pair of Kings in the hole.

Ducks
A pair of deuces (2s) in the hole.

Gay Waiter
A Queen with a Tray (3).

Broadway Straight
The highest possible straight, but not a straight flush. eg 10 J Q K A offsuit.

Bicycle / Wheel
The lowest possible straight. eg A 2 3 4 5.

The Dolly Parton
A straight running from 9 to 5. eg 9 8 7 6 5.

The Dead Man's Hand
Two pair, or a full house, of Aces with Eights. eg A A 8 8 K. So called because in the old west, Wild Bill Hickock was shot whilst playing poker. The hand he was holding - Aces and Eights.