Play proceeds through a succession of "hands", each hand consisting of a "deal", "the play" and "the show". At any time during any of these stages, if a player reaches the target score (usually 121), play ends immediately with that player being the winner of the game. This can even happen during the deal, since the dealer scores if a Jack is cut as the starter.

The deal

The players cut for first deal, and the person who cuts the lowest card deals. The dealer shuffles and deals five or six cards to each player, depending on the number of players. For two players, each is dealt six cards; for three or four players, each is dealt five cards. In the case of three players, a single card is dealt face down in the centre of the table to start the crib. Once the cards have been dealt, each player chooses four cards to retain, then discards the other one or two face-down to form the "crib" (also called the box), which will be used later by the dealer.At this point, each player's hand and the crib will contain exactly four cards. The player on the dealer's left cuts the deck and the dealer reveals the top card, called the "starter" or the "cut". If this card is a Jack, the dealer scores two points for "his heels".

The play

Starting with the player on the dealer's left, each player in turn lays one card face up on the table in front of him or her, stating the count—that is, the cumulative value of the cards that have been laid (for example, the first player lays a five and says "five", the next lays a six and says "eleven", and so on)—without the count going above 31. The cards are not laid in the centre of the table as, at the end of the "play," each player needs to pick up the cards they have laid.

Players score points during the play. For causing the count to reach exactly fifteen a player scores two points and play continues. Completing a pair (two of a kind) scores two points; three or four of a kind are counted as multiple pairs: completing three of a kind is the same as three different pairs, or 6 points, and four of a kind is 6 different kinds of pairs, or 12 points. A run of three or more cards (consecutively played, but not necessarily in order) scores the number of cards in the run.

If a player cannot play without causing the count to exceed 31, he calls "Go". Continuing with the player on his left, the other player(s) continue(s) the play until no one can play without the count exceeding 31. A player is obliged to play a card unless there is no card in his or her hand that can be played without the count exceeding 31 (one cannot voluntarily pass). Once 31 is reached or no one is able to play, the player who played the last card scores one point if the count is still under 31 and two if it is exactly 31. The count is then reset to zero and those players with cards remaining in their hands repeat the process starting with the player to the left of the player who played the last card. When all players have played all of their cards the game proceeds to the "show".

Players choose the order in which to lay their cards in order to maximize their scores; experienced players refer to this as either good or poor "pegging" or "pegsmanship". If one player reaches the target (usually 61 or 121), the game ends immediately and that player wins. When the scores are level during a game, the players' pegs will be side by side, and it is thought that this gave rise to the phrase "level pegging".

The show

Once the play is complete, each player in turn, starting with the player on the left of the dealer, displays his hand on the table and scores points based on its content in conjunction with the starter card. Points are scored for combinations of cards totalling fifteen, runs, pairs (multiple pairs are scored pair by pair, but may be referred to as three or four of a kind), a flush and having a Jack of the same suit as the starter card ("one for his nob [or nobs or nibs]", sometimes called the "right" Jack). A four-card flush scores four and cannot include the cut or starter; a five-card flush scores five.

The dealer scores his hand last and then turns the cards in the crib face up. These cards are then scored by the dealer as an additional hand, also in conjunction with the starter card. Unlike the dealer's own hand, the crib cannot score a four-card flush, but it can score a five-card flush with the starter.

All scores from 0 to 29 are possible, with the exception of 19, 25, 26 and 27. Players may refer colloquially to a hand scoring zero points as a “nineteen hand”.

Match

A match (much like tennis) consists of more than one game, often an odd number. The match points are scored on the cribbage board using the holes reserved for match points. On a spiral board, these are often at the bottom of the board in a line with 5 or 7 holes. On a conventional board, they are often in the middle of the board or at the top or bottom.

In a two-player game of cribbage, a player scores one match point for winning a game. Their opponent will start as dealer in the next game. If a player skunks their opponent (reaches 121 points before their opponent scores 91 points), that player wins two match points for that game. If a player double skunks their opponent (reaches 121 points before their opponent reaches 61), they score three or four match points for the game, depending on local convention. If a player triple skunks their opponent (reaches 121 points before their opponent reaches 31 points), they automatically win the match. Double and triple skunks are not included in the official rules of cribbage play and are optional. There are several different formats for scoring match points.

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The starter

The player on the dealer's left cuts the undealt portion of the deck (leaving at least 4 cards), and the dealer reveals the top card, called the "starter" or the "cut", placing it on top of the deck face up. (It is illegal to peek at any other cards in the deck during this process.) If this card is a Jack, the dealer scores two points for "his heels", also known as "his nibs", or simply "nibs". The game can end on a cut of a Jack for the dealer.

The play

In addition to scoring one or two points for the last card, players score points according to the following rules:

• fifteen-twos
  • two points for a cumulative total of exactly fifteen ("fifteen two")
• runs
  • three points for completing a run of three cards, regardless of the order in which they are laid (a 6, then a 4, then a 5 is a run of three even though they were not laid in order)
  • four points for completing a run of four
  • five points for completing a run of five
  • six points for completing a run of six
  • seven points for completing the run of seven; e.g. playing 2, 4, 6, A, 3, 5 and 7
• pairs
  • two points for laying a card of the same rank as the previous card, thus completing a pair
  • six points for laying a third card of the same rank (a "pair royal" or "trips")
  • twelve points for laying a fourth card of the same rank (a "double pair royal" or "quad")

The show

Once the play is complete, each player in turn receives points based on the content of their hand. Starting with the player on the dealer's left, players spread out their cards on the playing surface and calculate their score based on these four cards and the starter card:

• fifteen-twos
  • two points for each separate combination of two or more cards totalling exactly fifteen
• runs
  • three points for a run of three consecutive cards (regardless of suit)
  • four points for completing a run of four
  • five points for completing a run of five
• pairs
  • two points for a pair of cards of a kind
  • six points for three cards of a kind (known as a "pair royal", comprising three distinct pairs)
  • twelve points for four cards of a kind (a "double pair royal", comprising six distinct pairs)
• flush
  • four points for a flush, where all four cards in the hand are of the same suit, with an additional point if the starter card is also of that suit.
  • one point for holding the Jack of the same suit as the starter card ("one for his nob" or "... his nobs" )

Source

https://en.wikipedia.org/wiki/Cribbage

https://en.wikipedia.org/wiki/Rules_of_cribbage