LaTeX is a document preparation system for high-quality typesetting based on TeX. It is most often used for medium-to-large technical or scientific documents, but it can be used for almost any form of publishing. It is not a word processor; instead, it encourages authors not to worry too much about the appearance of their documents, but to concentrate on getting the right content.
prerex is an interactive (command-line) editor and a LaTeX macro support package that can be used to create very attractive and readable prerequisite charts. A graphical front-end for the editor also provides a prerex-enabled PDF viewer. A prerequisite chart is a network of course boxes linked by prerequisite and co-requisite arrows.