Vertex

A vertex is where two or more line segments meet. A corner.

Plural of vertex is vertices (pronounced “ver-tiss-ease”).

A vertical X (vertex) is covered in points which have two lines meeting.

Example 1

A pentagon has five vertices

Example 2

A square has four corners but these are four vertices too.

Example 3 

Where two lines meet is a vertex.

Example 4 

Example 5

A parabola can be thought of as two curves meeting, that is why mathematicians still call this a vertex. This can be the high point or low point of the graph.

Example 6