An adapter is a device that lets two things connect or work together when they wouldn't normally fit. When you travel to England and need to plug in your American phone charger, you use an adapter because British outlets have a different shape than American ones. The adapter doesn't change how your charger works; it just bridges the gap between your charger's plug and the foreign outlet.

Adapters solve mismatches between different systems. A USB adapter might let you plug a newer device into an older computer port.

You'll find adapters everywhere once you start noticing them: electrical adapters for plugging things in, travel adapters for different countries, and adapter rings that let photographers attach different lenses to their cameras.