Where does the expression “Ok” come from?

I watched this Vox video about the origins of one of the most common expressions I use each day, “Ok”:

I use this so often, I rarely pause to think about its origins. It’s a pretty interesting story too!

OK (or okay, ok, or k) might just be the most widely spoken word in the world. We use it so often, we barely notice it’s there: It’s in our speech, our writing, and even our computers. It feels like it’s been around forever, but it actually dates back to an obscure language fad in the 1830s where people facetiously misspelled abbreviations.