An altar is a special table or raised platform used for religious ceremonies and worship. In churches, synagogues, temples, and other houses of worship, the altar serves as the focal point where sacred rituals take place. A priest might stand at the altar during a religious service, or people might place offerings there as part of their worship.

Throughout history, people have built altars from stone, wood, or precious metals, sometimes decorating them elaborately to honor what they consider holy.

In Christian weddings, couples often exchange vows at the altar, which is why people say a bride or groom “walks down the aisle to the altar.” The phrase “sacrifice on the altar of” means giving up something important for a greater cause: a student might sacrifice sleep on the altar of studying for final exams, meaning they give up rest to achieve academic success.

Don't confuse altar with alter, which means to change something. Though they sound identical, an altar is a sacred table, while to alter your plans means to change them.