Most of the external harddrive have any one of the following interfaces: USB2.0, USB3.0, FireWire and eSATA. Your choices might be limited to the type of ports that you have in your system, but if you do have a range of ports available, then you do get to choose the best one for you.
USB (Universal Serial Bus) was developed during the 1990s, and was mainly designed to standardise the connection of peripherals, both for the sake of communication as well as to supply power. USB was the interface that effectively replaced the earlier interfaces such as the serial and parallel ports. It also replaced the need of separate power chargers for portable devices. The interface is so popular, that over 10 billion USB device have been sold till date.
USB 2.0 is one of the most common interfaces offered in most of the external hard drives, and one of the most easy to use too. The USB 2.0 was released in April 2000, and adds a higher maximum bandwidth of 480 mbps, which is also called “Hi-Speed”. USB2.0 has been available for so many years that it would not be an exaggeration if we said that each and every computer, including desktop PCs, laptops, netbooks and servers in both the worlds of Windows and Mac.
To eliminate this disadvantage of limited bandwidth, USB 3.0 was developed and announced on 17th November 2008. USB3.0 has transmission speeds of up to 5gbps, which is about ten times faster than the original USB2.0. This technology significantly reduces the time that is required for data transmission. In addition to this, it reduces power consumption, and is even downward compatible with USB2.0.
Some of the best USB3.0 compatible drives take full advantage of the amazing speed of this technology. However, some of the cheaper USB3.0 are not so fast, and for now, USB 3.0 is only available in very few PCs. That said, USB3.0 is the fastest interface of all, and hence the external hard drives with this interface tops the list of speedy drives.