Algebraic Notation
The standard way to write down chess moves, e.g. Nf3 or e4.
Algebraic notation names each square by file (a-h) and rank (1-8), so every move can be written as piece letter plus destination square, e.g. Nf3, exd5, O-O. It's the standard used in games, books, and this site's PGN viewer.
Related terms