The computer program par is a text formatting utility for Unix, written by Adam M. Costello as a replacement for the fmt command.
Par reformats paragraphs of text to fit into a given line length optimally, keeping prefixes and suffixes intact, which is useful for formatting source code comments. It also understands the conventions commonly used for quoting in email replies, and is capable of intelligently reformatting these several levels deep while rewrapping the text they quote.
Par can be evoked from text editors such as Vim or Emacs. Par has a good Unicode support, unlike the fmt command. Par also supports text justification, unlike the fmt. as of November 2010[update], Par is not provided as a part of Fedora Linux, and has to be compiled from source.