Cassettes are small, rectangular plastic cases that hold magnetic tape used for recording and playing audio. They became popular in the 1970s and 1980s, allowing people to listen to music and record their own sounds. Cassettes typically have two reels of tape inside, which move past a playback head in a cassette player. The invention of the cassette made music more portable and accessible. Many artists released albums on cassettes, and they were often used in walkmans and car stereos. Although digital formats have largely replaced them, cassettes still have a nostalgic appeal for collectors and music enthusiasts.