The Pawn

The Pawn moves one or two squares forward on its first move, after that, it may only move one square forward.
Pawns move forward on the file.
Pawns may not move backwards

                                                          Pawns capture only on the Diagonal.

When a pawn reaches the other side of the board, the 8th rank, it must be "promoted" to a Queen, or a Rook, or a Bishop, or a Knight.
It may not be promoted to a King.

Because a Pawn is promoted when it reaches the 8th rank, it is possible to have: 9 Queens, or 10 Rooks, or 10 Bishops, or 10 Knights.
It is very unlikely this will ever happen... but it is possible, and legal!