Perpendicular lines or axes form a coordinate system, with the intersection of the lines as the origin. A point in the plane is defined using an ordered pair of numbers as coordinates. The first number denotes travel distance from the origin along one axis, while the second signifies distance along the second axis. Conventions apply such that axis and coordinate names match (e.g., x-coordinate with x-axis, y-coordinate with y-axis).

Points can represent real-world and mathematical problems when graphed in the first quadrant of a coordinate plane. The interpretation of these coordinate values is contingent upon the context of the problem at hand.

Attributes of a two-dimensional category apply to all its subcategories, e.g., rectangles with four right angles include squares, thus all squares have four right angles.

Two-dimensional figures can be ordered in a hierarchy based on specific properties.