Why the letters on the a keyboard arranged so?

Why is the letters on 'Keyboard' arranged the way they are?

• They are arranged: QWERTYUIOP ASDFGHJKL ZXCVBNM Why is that?

• Answer:

  The first model constructed by Sholes used a piano-like keyboard with two rows of characters. His "Type Writer" had two features which made jams a serious issue. Firstly, characters were mounted on metal arms or typebars, which would clash and jam if neighboring arms were depressed at the same time or in rapid succession.[1] Secondly, its printing point was located beneath the paper carriage, invisible to the operator, a so-called "up-stroke" design. Consequently, jams were especially serious, because the typist could only discover the mishap by raising the carriage to inspect what he had typed. The solution was to place commonly used letter-pairs (like "th" or "st") so that their typebars were not neighboring, avoiding jams. While it is often said that QWERTY was designed to "slow down" typists, this is incorrect – it was designed to prevent jams[1] while typing at speed, yet some of the layout decisions, such as placing only one vowel on the home row, did have the effect of hobbling more modern keyboards