How are runs scored during the play stage of cribbage?

During the play stage of cribbage, runs are scored by forming a sequence of three or more cards, regardless of their suits or the order in which they were played.1

To score a run during play:
* The sequence must consist of at least three cards.1
* The cards must be played consecutively, meaning no intervening card can break the sequence.1
* The player who plays the card that completes the run receives one point for each card in that sequence.1

For example, if the cards played are 4, 6, and 5, the player who plays the 5 completes a three-card run and scores three points. If a player can subsequently add a card that extends the sequence (such as a 3 or a 7), they score points for the new, longer run.1