Variation

A series of moves logically connected with one another.

A variation can have various branches depending on the opponent's replies. A player's ability to calculate variations quickly and to foresee all possible branches is of enormous importance for achieving a successful result in a game.

In openings

The word variation is also widely used in openings. Here, however, the concept of a variation is broader: sometimes the word is used to mean an entire opening system, for example the Chigorin Variation of the Ruy Lopez:

In composition

In composition, a distinction is made between the main variation, thematic variations that reveal the main content of a problem or study, and side variations.