KK is an informal abbreviation used in text messages and other digital communications to mean "okay" or "message acknowledged". It is similar to nodding in person or saying "cool," "gotcha," or "alright". The abbreviation is typically used by teenagers, but people of all ages and backgrounds use it. The term "kk" is different from "okay" or "k" in that it is meant for more casual contexts between friends and family, and it can introduce a bit of levity and keep a text conversation from sounding too serious. However, it is not appropriate to use "kk" in work-related correspondence.