USB cable and portShort for Universal Serial Bus, USB (pronounced yoo-es-bee) is a standard that was introduced in 1995 by Intel, Compaq, Microsoft and other computer companies. USB 1.x is an external bus standard that supports data transfer rates of 12 Mbps and is capable of supporting up to 127 peripheral devices. The picture shows an example of a USB cable being connected into the USB port.

USB transfer speeds

USB 2.0, also known as hi-speed USB, was developed by Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips and was introduced in 2001. Hi-speed USB is capable of supporting a transfer rate of up to 480 Mbps and is backwards compatible, meaning it is capable of supporting USB 1.0 and 1.1 devices and cables.

USB 3.0 devices were first made available in November 2009 by Buffalo Technology, but the first certified devices weren't available until January 2010. The first certified devices included motherboards from ASUS and Gigabyte Technology. Dell began including USB 3.0 ports in their Inspiron and Dell XPS series of computers in April 2011. Today, many devices use the USB 3.0 revision for improved performance and speed, including USB thumb drives, digital cameras, external hard drives, MP3 players, and other devices.

As of 2012, USB 3.0 also known as SuperSpeed USB is the latest version of the USB protocol. Most new computers feature USB 3.0 ports built-in, offering data transfer speeds of up to five gigabits per second. USB 3.0 improved upon the USB 2.0 technology with speed and performance increases, improved power management and increased bandwidth capability (providing two unidirectional data paths for receiving and sending data at the same time).

USB connector variations

USB connectors come in many shapes and sizes as there are many different devices that utilize them. Every version of USB connector including standard, Mini, and Micro have two or more variations of connectors.

USB cables - Length and Type

USB cables are available in multiple lengths, from around 3 feet to just over 16 feet in length. The maximum length of a USB cable is 16 feet 5 inches (5 meters) for high speed devices and 9 feet 10 inches (3 meters) for low speed devices. These maximum lengths are due to data transfer timing and the risk of data loss if using longer cable lengths. However, by using USB hubs, you can connect two USB cables together to effectively extend the distance between the two devices being connected together.

There are different types of USB cables as well. As mentioned above, there are different transfer speeds (2.0 and 3.0) for USB. Similarly, there are different types of USB cables to match with those speeds. You can get a USB 2.0 cable for use with a device using USB 2.0 or a USB 3.0 cable for use with a device using USB 3.0.

There are also USB extension cables that can connect to one end of a USB cable (typically the end that would connect to the computer) to extend the length of the cable. However, you should still avoid extending the cable beyond the 16 feet 5 inches total maximum length limit, unless using a USB hub to connect another USB cable.

USB devices

Today, there are millions of different USB devices that can be connected to your computer. Below are just a few of the most common USB devices you'll likely find and use.

Related pages

Also see: Bus, Cable, Connection, Data cable, EHCI, Firewire, Motherboard terms, OHCI, PIIX, Port, UHCI, USB header