A Tsar was the title used for the emperors of Russia, similar to a king. The word comes from the Latin "Caesar," which means ruler. Tsars ruled from the 16th century until the early 20th century, overseeing vast territories and diverse populations. They held absolute power and were often seen as both political leaders and spiritual figures. One of the most famous Tsars was Peter the Great, who modernized Russia in the late 17th and early 18th centuries. He expanded the empire and established St. Petersburg as the new capital. The last Tsar, Nicholas II, was overthrown during the Russian Revolution in 1917, marking the end of the Tsarist era.