A package for typesetting graphs and diagrams using TeX. It is structured as several modules, each defining a custom notation for a particular kind of graphical object or structure. Example objects are arrows, curves, and frames. These can be organised in matrix, directed graph, path, polygon, knot, and 2-cell structure.

Xy-pic works with LaTeX, AMS-LaTeX, AMS-TeX, and plain TeX, and has been used to typeset complicated diagrams from many application areas including category theory, automata theory, algebra, neural networks and database theory.