TYPES OF KEYBOARDS
QWERTY Keyboard - Developed by Sholes in 1868 and is now the official standard of computer keyboards [ISO9995]. The layout of the QWERTY keyboard was designed for two finger typing and was designed to help prevent stuck keys. Now with new technology, stuck keys are no longer an issue; and with the position of the keys, the hands are held close together helping to cause Carpal Tunnel Syndrome. Given all the above problems, this is the most widely used keyboard because the lack of options, can be used without training, is used because of the difficulty of having to teach a different keyboard, and is cheap and easy to find.
Dvorak Keyboard - Developed by Dr. August Dvorak in 1936 as a solution to the outdated QWERTY keyboard. The layout of the keys on this keyboard make it easier and faster to type on when compared with other keyboards.
Chiclet Keyboard - Very small keyboard that was introduced with the PC Jr. with small keys spread out.
Below is a few of the keyboard layouts explained in the above section.
Articles source : http://www.computerhope.com/help/keyboard.htm#05