Keypads and keyboards enable a push button interface for users to input data to a computing device.  The simplest types of keypads available are basic 10 or 12 key input devices containing only numbers and maybe a couple of special characters, commonly seen in security and access point systems.  Often these keypads have a very basic electrical interface such as a switch matrix where the push of a button initiates electrical contact between two conductive paths.

Larger, alphanumeric keyboards are common in personal computing systems.  These keyboards typically have between 80 and 120 keys and often contain advanced control buttons used for adjusting audio volume or launching common applications.  These keyboards typically have a more sophisticated interface such as USB or Bluetooth.  Wireless keyboards are gaining popularity especially for use with mobile devices, but wired keyboards are still commonly used with desktop computers.