Editing Kristen Nygaard (section)

==Object-oriented programming==
With Ole-Johan Dahl, he developed the initial ideas for object-oriented programming (OOP) in the 1960s at the [[Norwegian Computing Center]] (Norsk Regnesentral (NR)) as part of the [[Simula]] I (1961–1965) and Simula 67 (1965–1968) [[simulation]] [[programming language]]s, which began as an extended variant and [[Subset|superset]] of [[ALGOL 60]].<ref name="CommonBase">{{cite report |last1=Dahl |first1=Ole-Johan |author-link=Ole-Johan Dahl |last2=Myhrhaug |first2=Bjørn |last3=Nygaard |first3=Kristen |author3-link=Kristen Nygaard |date=1970 |url=http://www.edelweb.fr/Simula/#7 |title=Common Base Language |publisher=Norwegian Computing Center |page=1.3.1 |access-date=14 November 2020 |url-status=usurped |archive-url=https://web.archive.org/web/20131225084408/http://www.edelweb.fr/Simula/scb-1.pdf |archive-date=2013-12-25}}</ref> The languages introduced the core concepts of object-oriented programming: [[Object (computer science)|objects]], [[Class (computer science)|classes]], [[inheritance]], virtual quantities, and [[Thread (computing)|multi-threaded]] (quasi-parallel) program execution. In 2004, the [[Association Internationale pour les Technologies Objets]] (AITO) established an annual prize in the name of Ole-Johan Dahl and Kristen Nygaard to honor their pioneering work on object-orientation. This [[Dahl–Nygaard Prize]] is awarded annually to two individuals that have made significant technical contributions to the field of object-orientation. The work should be in the spirit of the pioneer conceptual and/or implementation work of Dahl and Nygaard which shaped the present view of object-oriented programming. The prize is presented each year at the ECOOP conference. The prize consists of two awards given to a senior and a junior professional.

He conducted research for Norwegian [[trade union]]s on planning, control, and data processing, all evaluated in light of the objectives of [[organised labour]] (1971–1973), working together with [[Olav Terje Bergo]]. His other research and development work included the social impact of computer technology, and the general system description language DELTA (1973–1975), working with Erik Holbaek-Hanssen and Petter Haandlykken.

Nygaard was a professor at [[Aarhus University]], [[Denmark]] (1975–1976) and then became professor emeritus at the [[University of Oslo]] (part-time from 1977, full-time 1984–1996). His work in [[Aarhus]] and [[Oslo]] included research and education in system development and the social impact of computer technology, and became the foundation of the Scandinavian School in System Development, which is closely linked to the field of [[participatory design]].

Starting in 1976, he was engaged in developing and (since 1986) implementing the general object-oriented programming language [[BETA (programming language)|BETA]], together with Bent Bruun Kristensen, Ole Lehrmann Madsen, and [[Birger Møller-Pedersen]]. The language is now available on a wide range of computers.