KEYBOARD WHAT IS KEYBOARD :-      Keyboard is an input device that contains an arrangement of keys that help the user to interact with the computer and instruct the computer to perform a specific task by entering characters and functions into the computer system. KEYBOARD PARTS:- 1. ALPHANUMERIC KEYS These keys contains both the Numbers as well as the letters on the same key. 2. NUMERIC KEYS It is an  section of a keyboard containing 17 keys, usually on the far right that provides calculator type efficiency for entering numbers. 3. FUNCTIONAL KEYS Lined along the top of the keyboard from F1 to F12,this keys act as an operating system command interpreter or cause applications to perform certain actions. WORKING OF KEYBOARDThe keyboard contains contact layers beneath it which detect key  presses and it also contains 3 LED’s at the upper right corner to represent the indicator light for “NUM LOCK”, “CAPS LOCK ” and “SCROLL LOCK”. The contact layer contains of 3 layers of plastic out of which 2 are electrically conducting and comprises of an insulating layer between them to detect the key presses.     ON SCREEN KEYBOARD The On Screen Keyboard is an application that provides a visual keyboard on the display screen that can be used in place of the physical keyboard. The on screen keyboard allows user to enter text using a Joystick or a pointing device.              ADVANTAGES OF  ON SCREEN KEYBOARD1.The keyboards are very useful for physically disabled people who cannot type with their hand. By using touch to type, their work becomes more easier. 2.They can be easily maneuvered by using a pen or stylus.3.The on screen keyboards are not restricted to a particular language by making sure that the computer supports the specific language.4.  In case of financial transactions, the keyboard does not produce keystrokes and thus provides extra security towards hackers and identity theft.  DISADVANTAGES OF ON SCREEN KEYBOARD 1.The on screen keyboard obscures the work area.2.They are small and difficult to type in which increases the  typing errors.