Lout is a document formatting system similar in style to LaTeX. It offers a very full range of features, including PostScript, PDF, and plain text output, optimal paragraph and page breaking, automatic hyphenation, PostScript EPS file inclusion and generation, equation formatting, tables, diagrams, rotation and scaling, sorted indexes, bibliographic databases, running headers and odd-even pages, automatic cross referencing, multilingual documents including hyphenation (most European languages are supported, including Russian), formatting of computer programs, and more. Lout may be extended by writing definitions which are much simpler than the equivalent troff of TeX macros.