A knot group is a mathematical concept used in the study of knots, which are loops in three-dimensional space. Each knot can be associated with a specific group that captures the ways the knot can be manipulated without cutting it. This group helps mathematicians understand the properties and classifications of knots. The most common type of knot group is the fundamental group, which describes the loops around the knot. By analyzing the knot group, researchers can determine if two knots are equivalent or if they can be transformed into one another through a series of moves, known as Reidemeister moves.