Keyboard
The keyboard plugs into
the computer with a round connector, which can only fit one way. Recent
keyboards use a PS/2 connector, which is smaller than the old style keyboard connector.
The standard color coding scheme uses purple for the keyboard connector and
port, to make it easy to find the right port
for each connector. Not all manufacturers use the standard scheme.
The barrel of the connector usually has a mark or channel
or a flat area to show where the "top" of the plug is. That spot should match the "top" of the computer-side
port. In tower cases the "top" is not toward the top of the case when it is in use, but toward the "top" as it is laying open for being worked on.
Connecting or
disconnecting a device with a PS/2 connector can cause a power surge to your
motherboard, which can ruin it. The damage will not be visible, but it will
definitely not be repairable.
Some cases make it a little hard to get the keyboard plugged in firmly. When computer boots, it checks for the presence of a keyboard and will not continue if it can't find one. If this happens while your keyboard is plugged in, first shut down the computer and unplug the keyboard, then plug it up again. Try to be sure that the plug is fully seated. Then reboot.
Keyboards can fail, especially after a session with spilled liquids or crumbs. So keep such away from your computer working area. Your keyboard may recover from a swimming session after it dries out if the liquid did not leave anything behind like sugar or tea leaves.
Heavy use will eventually wear out the electrical contacts in the keyboard, as in any electrical device.