A czar (also spelled tsar) was the title given to the emperors who ruled Russia for hundreds of years, from the 1500s until 1917.

The czars held absolute power over their vast empire, making laws, commanding armies, and controlling the lives of millions of subjects. Some czars, like Peter the Great, modernized Russia and expanded its territory. Others ruled harshly, keeping tight control over their people. The last czar, Nicholas II, was overthrown during the Russian Revolution, ending centuries of czarist rule.

Today, Americans sometimes call a government official a czar when they're put in charge of handling a specific major problem. You might hear about an “energy czar” or “drug czar”: someone given broad authority to tackle one important issue. This modern usage borrows the idea of concentrated power from the historical czars, though these officials work within democratic systems rather than ruling as emperors. The comparison suggests someone with significant authority and responsibility, even if they don't wear a crown or live in a palace.