The keyboard is the main input peripheral used by all computers. The keyboard allows for user input and interaction with the computer. Much like many typewriters the keyboard has all the letters of the alphabet, numbers 0 - 9 and additional special operational keys, e.g. for adjusting the volume or going to your inbox directly. There are three different connection types: - USB is the most modern. You can recognize it by the rectangular connector. - PS/2 connectors are round. This type of connection is fairly commonly used by PC's. - Bluetooth is another modern (wireless) connection method.