GTG is an acronym that stands for "Got to go" or "Going to go". It is commonly used in online messaging and texting to indicate that the sender needs to leave the conversation or go offline for some reason. GTG can be used in both uppercase and lowercase letters, and it is often used as a replacement for "Bye" or "Good night". It is also related to other initialisms like BRB and TTYL, which imply shorter breaks. GTG originated in the 1990s to give status updates via IRC technology.