ABC is an imperative general-purpose programming language and integrated development environment (IDE) developed at Centrum Wiskunde & Informatica (CWI), in Amsterdam, Netherlands by Leo Geurts, Lambert Meertens, and Steven Pemberton.
[2] It is interactive, structured, high-level, and intended to be used instead of BASIC, Pascal, or AWK.
[5] Key features include: ABC was originally a monolithic implementation, leading to an inability to adapt to new requirements, such as creating a graphical user interface (GUI).
As of 2020[update], the latest version is 1.05.02, and it is ported to Unix, DOS, Atari, and Apple MacOS.
An example function to collect the set of all words in a document:[6] ABC has been through multiple iterations, with the current version being the 4th major release.