Collaborative software or groupware is application software designed to help people working on a common task to attain their goals. One of the earliest definitions of groupware is "intentional group processes plus software to support them." Regarding available interaction, collaborative software may be divided into real-time collaborative editing platforms that allow multiple users to engage in live, simultaneous, and reversible editing of a single file (usually a document); and version control (also known as revision control and source control) platforms, which allow users to make parallel edits to a file, while preserving every saved edit by users as multiple files that are variants of the original file. Collaborative software is a broad concept that overlaps considerably with computer-supported cooperative work (CSCW). According to Carstensen and Schmidt (1999), groupware is part of CSCW. The authors claim that CSCW, and thereby groupware, addresses "how collaborative activities and their coordination can be supported by means of computer systems." The use of collaborative software in the work space creates a collaborative working environment (CWE). Collaborative software relates to the notion of collaborative work systems, which are conceived as any form of human organization that emerges any time that collaboration takes place, whether it is formal or informal, intentional or unintentional. Whereas the groupware or collaborative software pertains to the technological elements of computer-supported cooperative work, collaborative work systems become a useful analytical tool to understand the behavioral and organizational variables that are associated to the broader concept of CSCW. Multi-user dungeon and Intelligence amplification#Douglas Engelbart: Augmenting Human Intellect Douglas Engelbart first envisioned collaborative computing in 1951 and documented his vision in 1962, with working prototypes in full operational use by his research team by the mid-1960s.