Most mice on the market today use a USB connector to attach to your computer. USB is a standard way to connect all kinds of peripherals to your computer, including printers, digital cameras, keyboards and mice. See How USB Ports Work for more information about this technology.
Some older mice, many of which are still in use today, have a PS/2 type connector. Instead of a PS/2 connector, a few other older mice use a serial type of connector to attach to a computer. See How Serial Ports Work for more information.