In knot theory, a link is one or more disjointly embedded circles in three-space. More informally, a link is an
assembly of knots with mutual entanglements. Kuperberg (1994)
has shown that a nontrivial knot or link in has four collinear points
(Eppstein). Like knots, links can be decomposed into basic units known as prime
links.
The term "link" is also used primarily by physicists to refer to a graph
edge.