A two-dimensional figure is a figure without thickness; it is flat.

A polygon is a two-dimensional figure
made up of non-overlapping, straight line segments.

The point where two line segments meet is a vertex, or corner.

A three-dimensional figure is any figure which is not flat.

A flat surface of a three-dimensional figure is a face.

An edge is where two faces meet.

A point where edges meet is a vertex, or corner.