Unto is an old-fashioned word meaning “to” or “toward.” You'll find it mostly in older books, poems, religious texts, and formal documents rather than everyday conversation.

In the Bible's Golden Rule, you might read “Do unto others as you would have them do unto you,” which means treat others the way you want to be treated. In Shakespeare's plays, a character might declare loyalty “unto the king.”

While unto sounds grand and ceremonial, it works much like the word “to” in modern English. “Give this unto her” means the same as “give this to her.” Today, people rarely use unto in normal speech or writing unless they're trying to sound deliberately old-fashioned or solemn. You might see it in wedding ceremonies, historical reenactments, or poetry that mimics older styles.

The phrase “a law unto themselves” survives in modern English, describing someone who makes their own rules regardless of what others think. But generally, when you encounter unto while reading older literature or historical documents, you can simply think “to” and understand the meaning perfectly.