Travel through Asia or Eastern Europe and you’ll find the most common English word people know is not yes, no, help or Coke – it’s OK. In markets, taxis and hospitals alike, people who know no other words will  hand you a calculator with a price on it and be able to agree in two simple letters.

But OK is a very strange word with an even stranger history. How did it become such a giant in world trading vocabulary?

There are numerous myths as to the origins of OK – the most common are that it is a bastardization of the Scottish “och, aye” or a phrase adopted from African slaves in the early American colonies. What we do know is it emerged during the late 1830s America as part of a trend for mis-spelling English words. OK stands for oll korrect, the irony of which is apparent.

Author Allan Metcalf has traced its origins to a newspaper joke in March, 1839, but it became famous when a New York social group introduced the term to Democratic hopeful Martin Van Buren, whose campaign came to be known as the Democratic OK Club.

By the early 1840s, the term was entrenched in officialdom, stamped on forms to show all was correct.

Michael Quinion has a thorough discussion on the history of OK at World Wide Words.

Mr Metcalf told NPR aid the word embodied the American philosophy of pragmatism because anything that is OK will do. In his book, he says it is so ubiquitous we don’t even notice it.

“It would not be much of an exaggeration to say that the modern world runs on OK,” Mr Metcalf wrote in OK.

“We write those letters on documents to mark our approval. We speak them to express assent, or just to say we’re listening. We accept a computer’s actions by clicking on OK. And we also use OK to introduce matters of importance, or recall an audience’s wander­ing attention.”

It’s hard to get through an American conversation without a “plentiful sprinkling” of OK, he said.

“It’s the easiest way to signal agreement, whether with a written OK on a document or an OK spoken aloud.”