What Does USB Do?
USB cables replace the huge variety of connectors that used to be standard for computer peripherals: Parallel ports, DB9 Serial, keyboard and mouse ports, joystick and midi ports… Really, it was getting out of hand. USB simplifies the process of installing and replacing hardware by making all communications adhere to a serial standard which takes place on a twisted pair data cable and identifies the device that’s connected. When you add the power and ground connections, you’re left with a simple 4-conductor cable that’s inexpensive to make and easy to stow.
What Kinds of Cables are Out There?
99% of host controllers will have a USB-A receptacle, so when you’re looking for a USB cable, you’ll usually be looking for a “USB A-to-something” cable. A lot of the time the USB-A end is assumed, since that’s the connector on most PCs, and cables will be named after the connector on the opposite end. Some smaller hosts use a Mini or Micro receptacle but they usually supply a pigtail adapter to USB-A.