Open line

	a	b	c	d	e	f	G	H
8th									8th
7th									7th
6th									6th
5									5
4th									4th
3									3
2									2
1									1
	a	b	c	d	e	f	G	H

The rook on the e line (marked with crosses) is on an open line as there are no pawns there. The rook can move to any square on this line.

An open line in chess is a line without pawns of any color. It typically arises from an open or semi-open game. Rooks or queens are advantageous in an open or half-open line as they make an attack easier.

Strategic characteristics

A strategic option for a rook or queen on an open line is to control the seventh or eighth row (or the first or second row for Black). Control of the seventh row (or the second row for Black) is typically worth at least one pawn, as most of the opponent's pawns are in this row. Aron Nimzowitsch wrote in his famous book Mein System that the primary goal of a rook or queen on an open line is to occupy the seventh or eighth row.

Many chess games are decided by this strategy. For example, a pawn sacrifice in the game Anand - Ivanchuk , Amber 2001, led by Anand to open the d-file. White then used this open line to station the rooks on the seventh and eighth rows, taking advantage of a weakness of the black a-pawn to win. White's dominance on the d-file allowed the rooks to attack deep within Black's defense.

Anand vs. Ivanchuk, 2001: example of creating an open line