Definition of Algol

ALGOL (short for ALGOrithmic Language) is a family of imperative computer programming languages originally developed in the mid 1950s which became the de facto standard way to report algorithms in print for almost the next 30 years. It was designed to avoid some of the perceived problems with FORTRAN  and eventually gave rise to many other programming languages (including Pascal). ALGOL uses bracketed statement blocks and was the first language to use begin end pairs for delimiting them. Fragments of ALGOL-like syntax are sometimes still used as a notation for algorithms, so-called Pidgin Algol.

Algol (β Per / Beta Persei) is a bright star in the constellation Perseus. It is one of the best known eclipsing binaries, the first such star to be discovered, and also one of the first (non-nova) variable stars  to be discovered. Algol is actually a three star system (Beta Persei A, B and C) in which the large and bright primary Beta Persei A is regularly eclipsed by the dimmer Beta Persei B. Thus, Algol's magnitude is usually near-constant at 2.1, but regularly dips to 3.4 during the several hour long eclipses which occur every 2 days, 20 hours and 49 minutes.