It’s OK To Read This

An OK article: How 'OK' took over the world.

It crops up in our speech dozens of times every day, although it apparently means little. So how did the word "OK" conquer the world, asks Allan Metcalf.

OK, I'll tell you.

On 23 March 1839, OK was introduced to the world on the second page of the Boston Morning Post, in the midst of a long paragraph, as "o.k. (all correct)".
How this weak joke survived at all, instead of vanishing like its counterparts, is a matter of lucky coincidence involving the American presidential election of 1840.
One candidate was nicknamed Old Kinderhook, and there was a false tale that a previous American president couldn't spell properly and thus would approve documents with an "OK", thinking it was the abbreviation for "all correct".
Within a decade, people began actually marking OK on documents and using OK on the telegraph to signal that all was well. So OK had found its niche, being easy to say or write and also distinctive enough to be clear.