# Point

A precise location or place on a plane. Usually represented by a dot.
Try this Move the points P or Q around with the mouse. Point R is not draggable.

A point is an exact position or location on a plane surface. It is important to understand that a point is not a thing, but a place. We indicate the position of a point by placing a dot with a pencil. This dot may have a diameter of, say, 0.2mm, but a point has no size. No matter how far you zoomed in, it would still have no width. Since a point is a place, not a thing, it has no dimensions.

Points are usually named by using an upper-case single letter. In the figure above, the points P,Q and R are shown. In this web site, points are shown either as a black dot or with a somewhat larger orange halo. This indicates the point can be dragged with a mouse.

• If a set of points all lie in a straight line, they are called 'collinear'. See Collinear definition
• If a set of points all lie on the same plane, they are called 'coplanar'. Coplanar definition

## Dragging hints

To drag a point:
1. Move the mouse over a point with an orange halo until a + or a hand symbol appears.
2. Press and hold the mouse button.
3. With the button down, move the mouse. The point will move.
4. Release the mouse button.

## Coordinate Geometry

In another branch of mathematics called coordinate geometry, points are located on the plane using their coordinates - two numbers that show where the point is positioned with respect to two number line "axes" at right angles to each other.

For more on this, see