Pawn

Pawns always move forwards and start off on the second and seventh ranks.

Pawns normally move one square forward only if that space is vacant. If the pawn has not moved it has the option of moving one or two squares only if those squares are vacant.

Move the pawn on e2 to e4.

Pawns can only capture pieces on either of the two squares diagonally in front of the pawn.

Here the black pawn on d5 is available to capture. Take it.

En Passant

Pawns have a special move called en passant.

When a pawn advances two squares on its initial move and ends the turn adjacent to an enemy pawn on the same rank, it may be captured en passant by the enemy pawn as if it had moved only one square.

This is only possible on the move immediately following the pawn's advance.

Black has just moved their b7 pawn to b5. You may now play en passant with the c5 pawn to b6 to capture it.

Notice that the f5 pawn cannot do the same and capture the g5 pawn as the opportunity is lost.

Promotion

Pawns have a second special move called promotion.

If a pawn advances to the last rank, then it is promoted to a queen, rook, bishop, or knight of the same color at the player's choice.

Advance the pawn on a7 to a8 and promote to any piece.