EMBOSS evolved from EGCG, a collection of programs written to extend the GCG package, originally written by the Genetics Computer Group of Wisconsin University. EMBOSS follows the general structure of GCG and sets out to reproduce and extend the functionality of GCG in an open source package. Currently, EMBOSS only runs on UNIX computers. The programs of EMBOSS can be run from the UNIX command line or from behind a number of Graphical User Interfaces (GUIs). EMBOSS offers a wide range of programs covering most aspects of sequence analysis. In addition, a number of well established public domain programs have been engineered to follow the conventions of EMBOSS and then incorporated into the package. Software developers from many places across the world have written programs for the EMBOSS package. Such contributions are encouraged from the user community and training is offered to aspiring contributors.