Move number

A move number orders the written game. Number 1 covers White's first turn and Black's first reply, number 2 covers the next pair, and so on. In 1. e4 e5 2. Nf3, e4 and e5 belong to move number 1, while Nf3 begins move number 2.

Periods after the number

• 1. e4 has one period because the following move is White's.
• 1... e5 has three periods, an ellipsis, when Black's reply is shown without the preceding White move.
• After Black moves, the number increases by one.

A numbered move should not be confused with a ply, also called a half-move. One turn by one color is one ply. Therefore 1. e4 e5 contains two plies but completes only one numbered move. This distinction appears in databases, computer analysis, and search-depth counts.

Move numbers help locate a moment in a game or a variation, which is an alternative move sequence. They are not part of Standard Algebraic Notation (SAN) for an individual move: Nf3 is SAN, while 2. is the label telling when it occurs.