Must OK only be written in capital letters?

Question

Whenever I write "ok" the spell checkers underline it with a red line and suggest that I should "OK". Not even "Ok" works. Why is that?

Answer 1

The proper spelling of the word is "okay." When writing an academic essay, acronyms such as "OK" should be written out in full. Feel free to use "OK" or even diminish it to "K" in your text messages. The important thing is to know the difference between formal and informal English. I hope that you're okay with this response!