The Cartesian Plane, also known as the coordinate plane, is a two-dimensional system used for graphing algebraic equations and representing geometric shapes. It was developed by French mathematician and philosopher Ren Descartes in the 17th century, hence the name "Cartesian" from his Latinized name, Cartesius. Descartes introduced the idea of using a grid system to plot points by using ordered pairs (x, y), linking algebra and geometry in what became known as analytic geometry. The Cartesian Plane is set up with two perpendicular number lines: the horizontal axis (x-axis) and the vertical axis (y-axis). These lines intersect at the origin (0,0), dividing the plane into four quadrants. The plane is used in various fields, including mathematics, physics, engineering, and computer graphics. Interestingly, Roman numerals are sometimes used to label the four quadrants: Quadrant I (I), Quadrant II (II), Quadrant III (III), and Quadrant IV (IV), moving counterclockwise from the upper right. This notation helps easily distinguish regions based on the signs of the x and y coordinates. Other names for the Cartesian Plane include the coordinate plane, xy-plane, and rectangular coordinate system. It remains one of the most fundamental tools in mathematics education and analysis.