An amplifier is a device that makes sounds louder by increasing their power. When a guitarist plugs an electric guitar into an amplifier, the small vibrations from the strings get transformed into much bigger, more powerful sounds that can fill a concert hall. Without an amplifier, an electric guitar barely makes any sound at all.

Amplifiers work by taking a weak signal and boosting it using electrical energy. Think of it like this: when you whisper, only people nearby can hear you, but if your whisper could be amplified, everyone in an auditorium could hear it clearly. Musicians use amplifiers for electric guitars, bass guitars, keyboards, and vocals. Audio systems in movie theaters, schools, and stadiums all rely on amplifiers to make sound reach every listener.

The word can also be used more broadly to mean anything that makes something stronger or more noticeable. A student might say that working in a group amplified their ideas, meaning collaboration made their thoughts more powerful and complete. When a small problem gets amplified, it becomes a bigger issue. The verb form is amplify.