Bottle caps are small, typically circular pieces of plastic or metal that seal the openings of bottles. They serve to keep the contents fresh and prevent spills. Commonly found on beverage bottles, such as those for soda, water, and beer, bottle caps can be either twist-off or pop-off types, depending on the design of the bottle. In addition to their practical use, bottle caps can also be collected or repurposed in various crafts. Some people enjoy creating art or jewelry from them, while others participate in bottle cap recycling programs. Overall, bottle caps play a significant role in packaging and consumer convenience.