In short: A sequence of moves. In the openings a variation is one of the paths an opening can take, and at the board a continuation you calculate in your head.
Also called line.
A variation is a sequence of moves. The word is used in two ways. In the openings a variation is one of the paths an opening can take, and many have names of their own, like the Najdorf Variation of the Sicilian, or the Gothenburg Variation, named after the city. At the board a variation is a continuation you calculate in your head: if I play this, and my opponent answers that, then I can...
Main line and sideline
The continuation played most and considered best in an opening is called the main line. What is played less often is called a sideline. A sideline isn't necessarily bad. It can be a good way to surprise an opponent who has only studied the main line.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
How variations are written
In annotations and books a variation is written in parentheses after the move it replaces, for example 4. Nc3 (4. e3 e6 5. Bxc4). Variations can have variations of their own, and then the parentheses multiply. The file format PGN writes them the same way.
Calculating variations at the board is a skill of its own. Read about candidate moves, about how the same position can be reached by different roads, transposition, and about opening theory.
Frequently asked questions
What is a main line?
The continuation in an opening that is played most and considered best. Variations played less often are called sidelines.
How is a variation written in annotations?
In parentheses after the move it replaces, for example 4. Nc3 (4. e3 e6 5. Bxc4). PGN writes variations in parentheses too.
Updated November 14, 2026
3… Nf6