Fundamental Concepts
1. The Tiny Dot · A mark of position with no size
A point is just a position, independent of where it sits on the plane.
A point marks a single position on the plane. We name it with a capital letter (P) and locate it with coordinates (x, y) — how far across (x) and how far up (y) from the origin O. Drag P — the coordinates change live; the dashed yellow lines show the projection onto each axis.