Origin square

Every move has a starting point. The origin square is the square the moving piece leaves. It is identified by board coordinates, which combine a letter for the file with a number for the rank.

From c3 to b5

8

7

6

5

4

3

2

a1

b

c

d

e

f

g

h

Start

Nb5

c3 is the square occupied by the knight before Nb5 and therefore its origin.

Before Nb5

The white knight occupies c3 immediately before the move. For this action, c3 is the origin square.

1. c3 is the square occupied by the knight before Nb5 and therefore its origin.

The origin tells us which piece moved, helps verify whether its route was possible, and distinguishes between identical pieces that could reach the same destination. In algebraic notation, the system that records moves with letters and numbers, the origin is usually implied but may be added partly or fully to remove ambiguity.

In a capture, the origin is still the square occupied by the capturing piece before it moved. In castling, a special move involving the king and a rook, technical systems may record each piece's origin and destination separately even though the rules count it as one king move.