MP3 (MPEG-1 Layer 3) is a coding standard for the compression and storage of audio content. This format allows audio files to be compressed by up to one twelfth of their original size while retaining acceptable sound quality. Using bit rates of 64 to 192 kbits/s, audio can run in real-time over the slower broadband connections, including single ISDN, and can be downloaded over a dial-up modem in a more realistic time – typically two to four times the actual running time.