A flanger is an audio effect used in music production that creates a sweeping, jet-like sound. It works by mixing two identical audio signals, with one signal delayed slightly. This delay is modulated over time, resulting in a series of peaks and troughs in the frequency spectrum, which gives the characteristic "whooshing" effect. Flangers are commonly used on electric guitars, keyboards, and vocals to add depth and movement to the sound. They can be found in various music genres, from rock to electronic, and are often used alongside other effects like chorus and phaser to enhance the overall audio experience.