What definition and How USB Ports work?

A USB port is a standard cable connection interface on personal computers and consumer electronics. USB ports allow stand-alone electronic devices to be connected via cables to a computer (or to each other).

USB stands for Universal Serial Bus, an industry standard for short-distance digital data communications. USB allows data to be transferred between devices. USB ports can also supply electric power across the cable to devices without their own power source.

 

Just about any computer that you buy today comes with one or more Universal Serial Bus connectors on the back. These USB connectors let you attach everything from mice to printers to your computer quickly and easily. The operating system supports USB as well, so the installation of the device drivers is quick and easy, too. Compared to other ways of connecting devices to your computer (including parallel ports, serial ports and special cards that you install inside the computer's case), USB devices are incredibly simple! 

Both wired and wireless versions of the USB standard exist, although only the wired version involves USB ports and cables.

What Can You Plug Into a USB Port?:

Many types of consumer electronics support USB interfaces. These types of equipment are most commonly used for computer networking:

• USB network adapters
• USB broadband and cellular modems for Internet access
• USB printers to be shared on a home network

For computer-to-computer file transfers without a network, USB keys are also sometimes used to copy files between devices. Multiple USB devices can also be connected to each other using a USB hub. A USB hub plugs into one USB port and contains additional ports for other devices to connect subsequently.

 

Usage Model:

Connect two devices directly with one USB cable by plugging each end into a USB port. If using a USB hub, plug a separate cable into each device and connect them to the hub individually. You may plug cables into a USB port at any time regardless of whether the devices involved are powered on or off. However, do not remove cables from a USB port arbitrarily, as this can lose or corrupt data. Follow instructions provided with your equipment before unplugging USB cables.
Many PCs feature more than one USB port, but do not plug both ends of a cable into the same device, as this can cause electrical damage.

 

USB-B and Other Types of Ports:

A few different types of physical layouts exist for USB ports. The standard layout for computers, called USB-B, is a rectangular connection point approximately 1.4 cm (9/16 in) length by 0.65 cm (1/4 in) height. Printers and some other devices may use smaller types of USB ports including a standard called USB-A. To connect a device having USB-B ports to a device with another type, simply use the correct type of cable with appropriate interfaces on each end.

Versions of USB:

The USB industry standard exists in multiple versions including 1.1, 2.0 and 3.0. However, USB ports feature identical physical layouts no matter the version of USB supported.

Alternative Technologies:

USB ports are an alternative to the serial and parallel ports available on older PCs. USB ports support much faster (often 100x or greater) data transfers than serial or parallel. For computer networking, Ethernet ports are sometimes used instead of USB. For some types of computer peripherals, FIreWire ports are also sometimes available. Both Ethernet and FireWire can offer faster performance than USB, although these interfaces do not supply any power across the wire.

• Printers connected to parallel printer ports, and most computers only came with one. Things like Zip drives, which need a high-speed connection into the computer, would use the parallel port as well, often with limited success and not much speed.
• Modems used the serial port, but so did some printers and a variety of odd things like Palm Pilots and digital cameras. Most computers have at most two serial ports, and they are very slow in most cases.
• Devices that needed faster connections came with their own cards, which had to fit in a card slot inside the computer's case. Unfortunately, the number of card slots is limited and you needed a Ph.D. to install the software for some of the cards.

The goal of USB is to end all of these headaches. The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer.

Just about every peripheral made now comes in a USB version. A sample list of USB devices that you can buy today includes:

• Printers
• Scanners
• Mice
• Joysticks
• Flight yokes
• Digital cameras
• Webcams
• Scientific data acquisition devices
• Modems
• Speakers
• Telephones
• Video phones
• Storage devices such as Zip drives
• Network connections