Universal Serial Bus (USB)

The Universal Serial Bus, or USB, is a standard for connecting peripherals to a computer through a single, widely adopted type of port. It was created to replace the many different connectors that earlier computers used for devices such as keyboards, mice, printers and external drives. By defining a common connector and communication method, USB allows a broad range of devices to attach to the same kind of socket, which greatly simplified connecting hardware.

USB uses a host-controlled, tiered design. One device, normally the computer, acts as the host and manages all communication on the bus, while attached devices respond to it. Hubs can be used to branch the connection so that one port can support several devices. A useful feature is hot plugging, meaning devices can be connected and disconnected while the computer is running, and the system detects them automatically and loads the software needed to use them without a restart.

In addition to carrying data, USB can supply electrical power over the same cable, which lets many small devices operate without a separate power source and allows phones and similar gadgets to charge from a USB port. The standard has gone through several versions, with later ones such as USB 2.0 offering substantially higher data rates than the original to keep pace with faster storage and other demanding devices. Its combination of simplicity, power delivery and broad device support made USB the dominant peripheral interface on personal computers.

Frequently asked questions

What problem was USB designed to solve?

It replaced the many incompatible connectors older computers used, giving most peripherals a single standard port and connection method.

What is hot plugging?

It is the ability to connect or disconnect a device while the computer is running, with the system detecting and configuring it automatically.

Can USB power a device?

Yes. USB carries electrical power alongside data, so many devices can run or charge directly from a USB port without a separate power supply.