USB makes adding peripheral devices extremely easy. With USB-compliant PCs and peripherals, you just plug them in and turn them on. USB makes the whole process automatic. It's like adding instant new capabilities to your PC. You never need to open your PC, and you don't need to worry about add-in cards, DIP switch settings or IRQs.

Another USB feature is "hot-swapping".  You no longer need to shut down and restart your PC to attach or remove a peripheral. Just plug in the new device and the PC automatically detects the peripheral and configures the necessary software.

USB also lets you connect many peripherals at one time. Many USB PCs come with two USB ports. And special USB peripherals -- called USB hubs -- have additional ports that let you "daisy chain" multiple devices together.

Most PCs, including laptops on the market today are fully USB-ready...ready for USB digital cameras, scanners, printers, computer telephony products, digital speakers and digital gaming devices.

 Devices can be attached to and detached from the computer without turning off the system. No jumper or IRQ settings are necessary.

Plug-and-Play:

Once the device is connected to the computer, the system automatically recognizes the device connected and installs the appropriate drivers.

127 peripherals:

USB makes it possible to simultaneously use and connect up to 127 devices to a single bus. The computer typically has 2 USB ports, so USB hubs are used to connect additional devices to the computer. USB hubs have multiple USB ports for connection of USB devices and for daisy chaining one or more hubs.

Point to point connection:

USB enables devices to be connected in any order, eliminating the need for external terminators.

Bus-powered and self-powered:

USB supports both bus-powered and self-powered devices. Good examples of bus-powered and self-powered devices are USB hubs. USB hubs can draw power either from the host device (bus-powered) or from an external AC power supply (self-powered). Each downstream port on a bus-powered hub typically supplies up to 100 mA. On the other hand, each downstream port on a self-powered hub typically supplies up to 500mA.