an index typewriter with a circular keyboard
The 1874 Sholes & Glidden typewriters established the QWERTY layout for the letter keys that is used nowadays in Anglophone countries for virtually all computer keyboards and the majority of other keyboards. Other nations using the Latin alphabet may use variants of the QWERTY layout, for example the French AZERTY layout.
The QWERTY design was based on the predicament that if typists proceeded too quickly, the arms of the original typewriters would jam. Most of the vowels, for example, are typed with fingers that are among the least dexterous on the hand. Though an akward layout was thus neccesitated, the word "typewriter" can be spelled using letters all on the top row, something that early salesmen could perform without having to learn how to type.
Radically different layouts such as the Dvorak keyboard have been proposed but have not been able to replace the QWERTY layout, despite the advantages claimed by their proponents. The Dvorak layout was introduced after the mechanical reason for the QWERTY layout became obsolete, and instead laid frequently used letters very close to one another, in order to minimize movement of the fingers while typing most words.
Many non-Latin alphabets have keyboard layouts that have nothing to do with QWERTY. The Russian layout, for instance, puts the common trigrams ыва, про, and ить on adjacent keys so that they can be typed by rolling the fingers. The Greek layout, on the other hand, is a variant of QWERTY.
