The Universal Serial Bus (USB) specification was designed to allow PCs to support more peripheral devices without adding serial or parallel connections to an already overburdened pile of cables. It also allows devices that don't need a permanent connection to the PC (such as digital cameras and audio players) to plug in and out only as needed, without having to reboot, much less open the box every time you needed it.
Nearly all PCs produced since the late 1990s have included at least two ports based on v1.1 of the USB specification. Devices built to this specification move data to and from the device to the PC at speeds between 1.5 and 12 megabytes per second (MBps). USB V2.0 permits much faster transfer speeds (up to 480 MBps), and so now you see even portable hard drives plugging into USB 2.0 ports and moving data swiftly.
Among the types of devices you'll see that plug into a USB port are keyboards, mice, modems, scanners, printers, digital cameras, webcams, and network cards (both wired and wireless).
The Linux kernel has supported the USB standard since v2.2.18, so all recent versions of SUSE Linux support at least USB 1.1 through the uhci kernel module. Developers working on the 2.6 kernel created the ehci module to support USB 2.0 and have since included compatible modules for earlier kernel versions, going back to v2.4. Still, some USB devices still have problems, mainly wireless (802.11 b) network adapters, scanners, and some webcams.
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