What does 'BTW' stand for?

“What does ‘BTW’ stand for?” — “By the way.” BTW is an informal initialism used to add a side comment, introduce a related topic, or mention something the writer nearly forgot. For example: “BTW, the meeting starts at nine.”

The expression “by the way” long predates the internet. Online communities shortened it to BTW because early chat rooms, bulletin-board systems, and instant messaging rewarded faster typing and fewer keystrokes. The abbreviation later spread through email, texting, forums, and social media, where it remains widely recognizable.

A common mix-up is treating BTW as identical to FYI (“for your information”). They overlap, but BTW usually signals an aside or conversational shift, while FYI introduces information the reader is expected to know. BTW is also normally casual; spelling out “by the way” is more natural in formal writing. In lowercase—“btw”—it has the same meaning and often feels even more conversational.