# Decision variable

### From Glossary

A decision variable represents a problem entity for which
a choice must be made. For instance, a decision variable might
represent the position of a queen on a chessboard, for which there
are 100 different possibilities (choices) on a 10x10 chessboard or the start time of an activity in a scheduling problem.
Each possible choice is represented by a value,
hence the set of possible choices constitutes the domain that
is associated with a variable.