O.K. or “Oll Korrect” was originally a corny joke amongst Boston intellectuals in 1830s Boston who would intentionally misspell abbreviations.
The Boston Post printed in what is the first known print of the word OK in 1839. Martin Van Buren even adopted the idiom during his 1840 reelection campaign as a nickname. His supporters called him “Old Kinderhook” after the New York town where he was born.
Van Buren lost the election, but OK took off, emerging from slang into practical use thanks to the invention of the telegraph in 1844. It was easier to tap out the word “OK” versus anything else for operators on the railroad to confirm receipt.
Part of the reason OK continued to supplant itself into vernacular in the 20th century was the way in which marketers used the letter “K.” Very few words started with the letter K, so brand strategists modified the C in words like Kraft, Kleenex, Krispy Kreme, and Koolaid to sell products.
Today, OK is universal. Used as an adjective, noun, verb, and adverb, it is most commonly understood as “the ultimate neutral affirmative.” As Alan Metcalf writes in OK: The Improbable Story of America's Greatest Word, OK does the “affirming without evaluating.” People use the word to convey the acceptance of information and not necessarily its confirmation.
So the word OK started off as awkwardly as it persisted. Yet, there never goes a day where you can avoid the ubiquity of the two-letter word.