coordinate plane
Think of a city laid out as a grid: to find a building you say how far east and how far north it sits. The coordinate plane works the same way. It is a flat surface with two number lines crossing at right angles, and every point on it has its own “address.”
The horizontal number line is the x-axis and the vertical one is the y-axis; they cross at the origin (0,0). A point is named by an ordered pair (x, y), where x tells you how far left or right to go and y tells you how far up or down. The two axes split the plane into four quadrants.
This idea, often credited to René Descartes, is the bridge between algebra and geometry: an equation in x and y becomes a picture (a curve or line), and a picture can be described by an equation. That is why we can “graph” equations at all.
To plot (3, -2): start at the origin, move 3 units right (positive x), then 2 units down (negative y).
Reading horizontal first, then vertical.
Order matters: (3,2) and (2,3) are different points. Always read the x-coordinate first, then the y-coordinate.