The Tatra K2 was the first production articulated tramcar built by KD Tatra between 1966 and 1983, following the failure of the experimental K1 which never entered production. It was noted that the main problem with the K1 was with the new electrical equipment, and therefore the same electrical equipment of the T3 was incorporated into the new K2. The prototype entered service in 1966 as Prague tramcar number 7000, where it spent only a short spell before being transferred to Most, and then again moved to Brno. Production of the K2 on a mass scale started the same year, and many examples remain in service to this day, albeit most having been extensively modernised. The modernisation of the K2 fleet in Brno, the biggest customer of the type, included the complete re-modelling of the front end, and the upgrading of their electronic equipment. These modernised examples were labeled K2R, whereby the 'R' stands for 'reconstructed'.