USB and Firewire are very similar interfaces but both have distinct value in the computer and digital device market. This guide is not a technical guide but rather a practical guide to the uses, pros and cons to each interface format. FireWire (also known as i.Link or IEEE 1394) is a high speed format that comes in 2 speeds (400 and 800 Mbps) USB (Universal Serial Bus) is either high speed in the 2.0 variety (480 Mbps) or relativly low speed (12 Mbps) in the 1.1 variety. Many people are confused by the two formats and some see them as competing formats. In practice, they both compete and compliment each other. There are basically three groups of products that use these formats that I will devide into devices that are better with Firwire. Devices that are better with USB and the broad overlap. Device that are better with Firewire: DV Camcorders use Firewire so overwhelmingly that many people see Firewire as a DV cam cable. It is also used in professional audio interfaces, prefessional scanners as well as external optical and hard drives. Devices that are better with USB USB has replaced serial ports as well as parrallel ports for printers and PS2 ports for mice and keyboards. As you can see, Firewire is often times used for professional purposes and USB is more of a consumer format. With the advent of USB 2.0 and the higher speeds it is cabale of, it blurred the lines between the two. Overlap: Both formats are now used for many things such as external drives where often both USB and Firewire are on the same device. There are two important differences that result in pros and cons for both: size and latency. USB is capable of much smaller device sizes as evidenced by the super small keychain flash drives on the market. The reason for this is that USB is much more dependant on the host computer and has the effect of slowing the system down (only slightly on modern systems). The advantage here is that USB is less expensive to implement. Firewire on the otherhand, while being more expensive to implement and being used only in somewhat larger devices has a huge advantage in a key area for real time applications such as video and audio: Latency. Latency is simply the time it takes for data to get from the device to the computer (and back to the device where applicable) While a slight delay is no problem for your printer for instance, it is crucial for professional audio interfaces where instant feedback is crucial. Conclusion: For the vast majority of devices, either format with get the job done quite well. For small consumer devices and common items like printers, keyboards and mice, USB is great. For high end prefessional audio and video equipment, Firewire is a must. Both formats are a compliment and should enjoy a long life in the computer and digital device industry.