The x and y axes are part of the Cartesian coordinate system, also called the rectangular coordinate system. Coordinates on this system are located by their distance from perpendicular lines (the x and y axes) that intersect. Every line, figure and point in coordinate geometry can be drawn in a coordinate plane using the Cartesian coordinate system.

René Descartes, a French philosopher and mathematician, invented the Cartesian coordinate system. In 1637 he published a book, "Discourse on the Method of Reasoning Well and Seeking Truth in the Sciences," that included a section called "La Géometrie," or Geometry. In this section Descartes described the Cartesian coordinate system, pairing geometry and algebra for the first time.

The Cartesian coordinate system comprises two number lines, one horizontal and one vertical. The horizontal line is known as the x-axis and the vertical line is called the y-axis. These axes intersect to form four quadrants. Because the x and y axes are perpendicular to one another, they intersect only once, in a place called the origin. Coordinates are measured by a set length that equates to distance from the origin.

Coordinates are written as (x,y), where x stands for the value on the x (horizontal) axis and y stands for the value on the y (vertical) axis. The place where the x-axis and y-axis meet is at a zero value on both the x and y axes. Because the x and y axes both intersect at zero, the coordinate of their point of intersection is described as (0,0).

A point located in quadrant I, on the upper right, has a positive x and y coordinate value, for example (1,1). A point located in quadrant II, on the upper left side, has a negative x and positive y coordinate value, for example (-1,1). A point in quadrant III, on the lower left side, has a negative x and y coordinate value, for example: (-1,-1). A point in quadrant IV, on the lower right side, has a positive x and negative y coordinate value, for example (1,-1).