Cartesian coordinates are a system used to define the position of points in a two-dimensional or three-dimensional space. In a two-dimensional space, each point is represented by an ordered pair of numbers (x, y), where 'x' indicates the horizontal position and 'y' indicates the vertical position. The point is located on a grid formed by two perpendicular lines called axes. In three-dimensional space, Cartesian coordinates extend to an ordered triplet (x, y, z), adding a third axis, which represents depth. This system allows for precise location identification and is widely used in mathematics, physics, engineering, and computer graphics.