An OKB (Russian: Опытное конструкторское бюро - Opytnoe Konstructorskoe Byuro - Experimental Design Bureau) was, during the Soviet era, an engineering design team. These were each assigned a number by the state, and often named after their head designer - for example, OKB-51 was headed by Pavel Sukhoi, and eventually became known as OKB Sukhoi. Successful and famous bureaux often retained this name even after the death or replacement of that designer. The Union of Soviet Socialist Republics (USSR) (Russian: (СССР) listen; tr. ... Pavel Osipovich Sukhoi Pavel Osipovich Sukhoi (Павел Осипович Сухой) (July 22, 1895 – September 15, 1975) was a Belarusian aircraft constructor and designer. ... Sukhoi (Сухой) is a major Russian military fighter aircraft manufacturer. ...
These small state-run organisations were not intended for mass production of aircraft, rockets, or other vehicles or equipment that they designed. However they usually had the facilities and resources to construct prototypes. Those designs accepted by the state for mass production were then assigned to a state factory.
OKB is a transliteration of the Russian acronym for "Опытное конструкторское бюро" - Opytnoe Konstructorskoe Byuro, meaning Experimental Design Bureau.
During the Soviet era, OKBs were closed institutions working on design and prototyping of advanced technology, usually for military applications.
A bureau was officially identified by a number, and often semi-officially by the name of the lead designer - for example, OKB-51 was lead by Pavel Sukhoi, and eventually became known as OKBSukhoi.