The LaTeX Track Changes (LTC) system allows collaborators on a LaTeX writing project to view changes in .tex files. Author changes are presented in color in an Emacs buffer or in a stand-alone Java application. The history of changes is stored by managing the writing project in the git or svn version control system, which also facilitates collaboration by enabling concurrent and distributed document updating.
In contrast to Microsoft Word, for example, changes do not need to be manually accepted or rejected. Instead, the full history of document changes is always available, but the author can use LTC to filter how recent a set of changes are displayed at a given moment, such as showing changes made since the author last worked on the document.
Our current version provides a stand-alone Java application to view changes and edit text, as well as an Emacs minor mode. Plugins for LTC to support other popular LaTeX editors such as TeXShop are planned or could be implemented by the community using our open API.