Everyone who can use a computer is familiar with the QWERTY keyboard layout. After all, it was the typewriter QWERTY layout before it made the jump to computer keyboards. Most people have probably heard the story of why the QWERTY layout came to be, too--supposedly, when keys were first arranged alphabetically on a 19th century typewriter, the most commonly used letter combinations would create some problems. This is the story Wikipedia tells: "characters were mounted on metal arms or typebars, which would clash and jam if neighboring arms were pressed at the same time or in rapid succession." Thus the keyboard layout was carefully arranged to minimize problematic arrangements and keep typewriters functioning without nasty jams.
But that might not be the truth. Smithsonian Mag has taken an interesting dive into the history of the typewriter and the QWERTY layout, and there are some flaws in the old story. For example: why are E and R adjacent, when "ER" is one of the most commonly used letter combinations in the English language? Smithsonian Mag turned up a lot more in their research.
One theory is that the keyboard layout was influenced by Morse code. "Kyoto University Researchers Koichi Yasuoka and Motoko Yasuoka...tracked the evolution of the typewriter keyboard alongside a record of its early professional users," writes Smithsonian. "They conclude that the mechanics of the typewriter did not influence the keyboard design."
Here's what the researchers had to say about QWERTY:
“The code represents Z as ‘· · · ·’ which is often confused with the digram SE, more frequently-used than Z. Sometimes Morse receivers in United States cannot determine whether Z or SE is applicable, especially in the ﬁrst letter(s) of a word, before they receive following letters. Thus S ought to be placed near by both Z and E on the keyboard for Morse receivers to type them quickly (by the same reason C ought to be placed near by IE. But, in fact, C was more often confused with S)."
Research also revealed that the QWERTY typewriter's creator tried out many different letter arrangements, even after QWERTY had caught on. It's possible, even likely, that the arrangement wasn't necessarily considered the best or the most efficient--it was simply what they'd settled on when they sold the design to Remington, which drove the production of early typewriters.
The full story contains a whole lot more QWERTY history, but it seems like the layout was popularized in the 19th century for the same reason it's still in use today: Once everyone learned it, there was no convincing them to try something else.