The QWERTY keyboard was originally designed to prevent key jamming.
Why it is true
In early typewriters, adjacent keys used together would jam frequently. The QWERTY layout separated the most common letter pairs to force typists to type in a more alternating manner, preventing mechanical failures.
Source: Smithsonian Magazine
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.