What does "BTW" mean on Facebook?

BTW is an acronym used on Facebook that means “by the way”. BTW, or by the way, is used the same way in social media and electronic communications as it is in everyday speech; however, it is generally not used in professional communications, because it creates a negative, unprofessional impression.

Internet acronyms are especially useful on social media sites, such as Twitter, that have a character limit on each post. Acronyms save time when writing messages, but they also convey that the user understands social media lingo. Emoticons are often used in the same way to convey emotions, in shorthand.