Input devices are too often taken for granted by users. But if the idea is as much to put data in as to get data out, then the input devices we use are critical. The most ubiquitous of input devices, keyboards tell the BIOS and ultimately the CPU which keystrokes you've entered.
Contact types are older, using a mechanical switch to close a circuit with each keystroke.
Your preference for audible and tactile feedback may determine your preferences here. Capacitance keyboards tend to last longer than contact keyboards, but cost a bit more. Also check out the new wireless keyboards. Actually, a mouse is just one type of pointer device used by various machines to input data. Today's mice no longer use the serial port or a bus card to connect, preferring to connect either through a USB port or directly to the motherboard.