A locus is a set of points that satisfy a specific condition or a group of conditions in a mathematical space. For example, in a two-dimensional plane, the locus of points equidistant from a fixed point forms a circle. This concept is fundamental in geometry and helps in understanding shapes and their properties. In algebra, a locus can also represent the solution set of an equation. For instance, the locus of points that satisfy the equation of a line, such as y = mx + b, consists of all points (x, y) that lie on that line. Understanding loci is essential in fields like geometry, trigonometry, and calculus.