ALGOL is a structured, high-level programming language with advanced computational and I/O capabilities. ALGOL also provides the most complete process initiation and control capabilities of any language available.

Closely related to ALGOL are several extended versions of the ALGOL language. DCALGOL is an extended ALGOL that includes some system control and data communications interfaces. DMALGOL includes special constructs for data management software. BDMSALGOL contains extensions for accessing Enterprise Database Server databases. In the following discussion, the features described are available in each of these languages, except where otherwise noted.

For further information about the ALGOL tasking features discussed in the following subsections, refer to the ALGOL Programming Reference Manual, Volume 1: Basic Implementation.