OK "is an English word that used to express assent, agreement, or acceptance. It is often translated as a borrowed word in many other languages and is described as a word that can be widely understood in the world.
There has been much effort to explain the emergence of this phrase, which seems to have been involved in popular use in the US during the 19th century. Most of them are speculation.
It does not seem at all likely from the language and the history of evidence, that comes from the Scottish expression or from the Greek ola castle ("is good"), the Chocktaw Indian oke okeh ('it is so'), French aux Cayes (' From Cayes', a port in Haiti with a good rum reputation), or au quai ('to the quay', as supposedly used by French-speaking dockers), or the initials of a railway freight agent called Obediah Kelly who is said to have written them on documents he had checked.
Its oldest text references result from its use as a slogan of the Democratic Party during the 1840's presidential election. Their candidate, President Martin Van Buren, was placed "Old Kinderhook" and then his supporters formed "klabin OK". This certainly helped popularize this term (though he failed to re-elect President Van Buren).
In fact, the exact explanation is that the term originates from an abbreviation for "Oll Korrect", a jokey misspelling of "ALL CORRECT" that was current in the US in the 1830s. After that, "OK" would return to one of The most used expressions not only in the US but also all over the world.
