BibTeX is a program and file format designed by Oren Patashnik and Leslie Lamport in 1985 for the LaTeX document preparation system. The format is entirely character based, so it can be used by any program (although the standard character set for accents is TeX). It is field (tag) based and the BibTeX program will ignore unknown fields, so it is expandable. It is probably the most common format for bibliographies on the Internet.