The full name of USB is Universal Serial Bus. USB supports the advantages of hot plug and play, so USB interface has become the main interface mode of MP3. USB has two specifications: USB 1.1 and USB 2.0.

USB 1.1 is a popular USB specification at present. Its transmission rate is 12 Mbps in high speed mode, 1.5 Mbps in low speed mode (b means bit), 1 MB/s (megabyte/second) = 8 Mbps (megabit/second), and 12 Mbps = 1.5 MB/s.

The USB 2.0 specification evolved from the USB 1.1 specification. Its transmission rate reaches 480 Mbps, converted to 60 MB/s, which is enough to meet the speed requirements of most peripherals. The Enhanced Host Controller Interface (EHCI) in USB 2.0 defines a compatible architecture with USB 1.1. It can drive USB 1.1 device with USB 2.0 driver. That is to say, all devices supporting USB 1.1 can be directly used on the interface of USB 2.0 without worrying about compatibility issues, and accessories such as USB cables, plugs and so on can also be directly used.

USB 2.0 standard further increases the interface speed to 480 Mbps, which greatly reduces the transmission time of MP3 music files.