LaTeX is a free document preparation mark-up language that allows for high quality typesetting. It is used most often for medium to large size documents but can be used for any situation. It is an alternative to using a word processor to format your document. In LaTeX the text of the document is marked-up using LaTeX commands to determine formatting. It is similar in concept to CSS and HTML.

LaTeX contains features for:

• Typesetting journal articles, technical reports, books, and slide presentations.
• Control over large documents containing sectioning, cross-references, tables and figures.
• Typesetting of complex mathematical formulas.
• Advanced typesetting of mathematics with AMS-LaTeX.
• Automatic generation of bibliographies and indexes.
• Multi-lingual typesetting.
• Inclusion of artwork, and process or spot colour.
• Using PostScript or Metafont fonts.

For further information see: http://www.latex-project.org/intro.html