MP3 is the ubiquitous lossy audio format that shrank the music industry onto the early Internet. Employing perceptual coding, it removes frequencies masked by louder sounds, producing acceptable fidelity at 128‑320 kbps. The Fraunhofer team finalised MPEG‑1 Layer III in 1994, but it wasn’t until Winamp (1997) and Napster (1999) that MP3 exploded. Patent pools expired between 2012‑2017, freeing open‑source encoders like LAME. Streaming giants now favour AAC or Opus, yet MP3 remains the safest choice for maximum backward compatibility.