See: http://mathworld.wolfram.com/Vertex.html

A vertex in mathematics is a location where two or more lines or edges meet.

Divmod Vertex is an implementation of and interface to the Q2Q protocol.  It is
named for a vertext because it provides a way for peers on the internet to
establish connections with each other, e.g. to make their connection lines
meet, regardless of intermediary interference such as network address
translators and lack of naming information.