Cassette tapes are small, rectangular plastic cases that contain magnetic tape used for recording and playing audio. They were popular from the late 1960s to the early 2000s, allowing people to listen to music and record their own sounds. Each tape typically holds about 30 to 90 minutes of audio, depending on its length. To play a cassette tape, you need a cassette player, which has two spools that move the tape past a magnetic head. This technology was a significant advancement in music storage, paving the way for later formats like CDs and digital audio files.