The term Tsar refers to the title used by the emperors of Russia from the 16th century until the abdication of Nicholas II in 1917. It is derived from the Latin word 'Caesar' and signifies a ruler with absolute power. Tsars were known for their autocratic rule and played a significant role in shaping Russian history, culture, and politics. Tsars like Ivan IV (Ivan the Terrible) and Peter the Great are notable figures who expanded the Russian territory and modernized the state. The fall of the Tsarist regime marked the end of centuries of imperial rule, leading to the establishment of the Soviet Union.