From the manufacturer:
The most numerous and famous tank in the world was the Soviet T-34. It was designed by the Design Bureau of Kharkov plant number 183 under the leadership of M.I. Koshkin.
Its serial production was launched in 1940. It was the first mass-production tank with anti-projectile armor, a powerful diesel engine and a 76.2cm long-barreled gun. It was the world`s best tank up to the end of 1941.
The last modification T-34-85, with the enlarged 3-man turret and more powerful 85mm gun, was in production since January 1944.
The T-34 with 85mm guns (D-5T, later S-53 and ZiS0S53) became the main Soviet medium tank up to the end of WWII.
25,914 T-34-85 tanks were produced in three U.S.S.R. plants in 1944-46. The largest producer was Plant 183 in Nizhny Tagil.