The Universal Serial Bus (USB) is a serial bus standard to interface devices. This was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). This interface can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks,scanners,digital cameras, printers, personal media players,and flash drives.
USB supports three data rates:
A Low Speed (1.1, 2.0) rate of 1.5 Mbit/s (187.5 kB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.
A Full Speed (1.1, 2.0) rate of 12 Mbit/s (1.5 MB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. All USB Hubs support Full Speed.
A Hi-Speed (2.0) rate of 480 Mbit/s (60 MB/s).
The maximum length of a standard USB cable is 5.0 meters (16.4 ft)
The IEEE 1394 interface is a serial bus interface standard, for high-speed communications and isochronous real-time data transfer, frequently used in personal computers, digital audio and digital video. The interface is also known by the brand names of FireWire (Apple's name) and i.LINK (Sony's name).
FireWire has replaced Parallel SCSI in many applications, due to lower implementation costs and a simplified, more adaptable cabling system. FireWire is also available in wireless, fiber optic and coaxial versions using the isochronous protocols.
FireWire can connect up to 63 peripherals in a tree topology.
USB vs. Firewire
Although high-speed USB 2.0 runs at a higher signaling rate (480 Mbit/s) than FireWire 400, typical USB PC-hosts rarely exceed sustained transfers of 280 Mbit/s, with 240 Mbit/s being more typical. This is likely due to USB's reliance on the host-processor to manage low-level USB protocol, whereas FireWire delegates the same tasks to the interface hardware.
FireWire 800 is substantially faster than Hi-Speed USB.