A beach ball is a large, lightweight, inflatable ball designed for playing games at the beach or pool. Beach balls are usually made of thin, colorful plastic panels glued together, with a small valve where you blow air into them. Because they're filled with air and made of such light material, beach balls float on water and drift lazily through the air when you hit or throw them.

The slow, unpredictable way beach balls move makes them perfect for casual games where the goal is fun rather than competition. At the beach, you might bat one back and forth with friends in the shallow waves. At concerts or sporting events, people sometimes toss beach balls through the crowd, with everyone helping keep them aloft. Their size (often two to three feet across) and gentle bounce mean even small children can play with them safely.

Beach balls became popular in the 1930s and quickly became a symbol of summer fun and relaxation. Today, when someone inflates a beach ball, it usually signals that serious competition is over and it's time to just enjoy yourself.