Consider a co-ordinate.

For example, (4,3).

It is a point.

It has a position, but no height or width or length.

It is zero-dimensional.

Now imagine stretching that point into a line.

It has become one-dimensional.

It has a length. (Measured in cm, for example.)

Imagine stretching the line out into a square.

It is now two-dimensional. (2D)

It has an area. (Measured, for example, in cm2.)

Stretching this square out results in a cube.

This is a 3D shape. (Three-dimensional.)

It has a volume, which could be measured in cm3.

Notice how the power after the unit shows us how many dimensions are involved.

  • cm = cm1 (one-dimensional)
  • cm2 (two-dimensional)
  • cm3 (three-dimensional)

We could go further, but we’ll leave it there for now.