Here are some poker terms to help you understand this great game 100%.
All In: See 'Tapped Out'.
Betting Round: If any cards of players' hands are up, betting usually begins with whoever is showing the highest hand. Some people play that in high/low games, the first round of betting starts with the lowest showing hand and all later rounds start with the highest. If no cards are showing, the betting should start with a different player each round, beginning with the player to the left of the dealer and rotating to the next player clockwise each round. A round consists of a series of bets until everyone has called or folded.
Declare: Announcing whether you're trying for the high hand, low hand, or both. Typically, this is done by secretly putting no chips in your hand if you're going low, one chip if you're going high, or two chips if you're going both. Everyone then opens their fists simultaneously.
Down: Face down, so that the value of the card isn't showing. Also known as 'In The Hole'.
Exchange: Discard cards from a hand and replace them with different cards, usually from the top of the deck.
High/Low: The highest hand and the lowest hand split the pot. In many high/low games, it is possible to win the entire pot by having the highest and the lowest hand (accomplished via wild cards, or by using different sets of 5 cards), but only if you declare that you're trying for both. If you try for both but don't win both (that is, someone else has the highest or the lowest hand), you win neither. When playing high/low, hands are compared against all other hands, not just the hands which are going the same way. Thus, if someone going high has a better low hand than all of the people going low, nobody going low wins (so the high hand gets the whole pot). If someone goes for both and fails, say by winning high but losing low, the high half of the pot goes to the low winner-- it doesn't go the second best high hand.
In The Hole: See 'Down'.
Natural: Without wild cards.
Perfect low: A perfect low is usually A-2-3-4-6. However, it can also be A-2-3-4-5 if you play that straights don't count when you go low, or it can be 2-3-4-5-7 if you play that Aces are always high, or 2-3-4-5-6 if you play both of the above.
Rank: Value of a card. There are 13 ranks in a deck of cards.
Roll: Flip a down card up.
Rolling Showdown: A showdown in which cards are stacked and revealed one at a time with a round of betting after each card is revealed.
Rotating Bet: Each round of betting starts with the next player clockwise. Typically, the player to the left of the dealer starts the first betting round. The 2nd round would thus be started by the player to his left, and so forth.
Showdown: The process of revealing hands and determining the winner.
Tap Out: This happens whenever a player bets all of his or her remaining money. If only that player and one other are still playing the hand, then the remaining cards for the hand are dealt out and no more bets are placed. If more than two players are still playing the hand, then a separate pot is created to hold the bets for the players who are not 'Tapped Out'. Betting continues as normal for those other players in the new pot. When the hand is over, if the player who tapped out wins, then that player gets the first pot and the player with the second highest hand gets the second pot. If the player who tapped out does not win the hand, then the winning player get both pots. Also known as 'All In'.
Trick: A set of cards, one card from each player, played one at a time in sequence around the table. Tricks are usually found in games like Hearts and Bridge, not in true Poker games.
Trump: One suit which is stronger than other suits. The lowest ranking card of a trump suit beats the highest ranking card of any other suit. Trump suits are used in trick-taking games and are not found in true Poker games.
Up: Face up, so that the value of the card is showing.
Bugs: Jokers that can represent any card if it helps accomplish a straight or a flush, but represent only aces (of any suit) if it goes towards some other kind of hand.