The Full form of BTW is By The Way. BTW is shorthand for By The Way. It is typically used by a person to change the subject during a conversation. It can be used as a post amble or a preamble to signify the change of subject. For example: BTW I like your watch (Here, BTW is a preamble, i.e., before the text), and I like your watch BTW (Here, BTW is a post amble, i.e., after the text). Of note, BTW is also occasionally used to mean “back to work”. “By the Way” is the most common meaning for BTW on WhatsApp, Snapchat, Twitter, Facebook, and Instagram.