BTW stands for "by the way." It is a conversational detour. You are talking about one thing, and you remember another. "BTW, did you pay the rent?" It is casual, quick, and often used in text messages and emails. It signals that the following information is not the main point, but it is still relevant. It is a parenthesis in digital speech.

The acronym has been around since the 1980s. It was common in bulletin board systems and early chat rooms. It is one of the few that survived into professional email. "BTW, the meeting moved to 3 PM." That is acceptable in most offices. It is informal but not rude. It saves typing. It keeps the message light.

Related acronyms

• FYI: for your information, more formal.
• BTW: by the way, casual.
• IMO: in my opinion.
• TBH: to be honest.

BTW can be passive-aggressive. "BTW, you left the dishes." The "by the way" softens the complaint. It makes it sound like an afterthought. But the reader knows it is the real message. The acronym is a tool. It can be used to inform or to nag. Tone is everything. In a text, it is often friendly. In an email, it depends on the subject line.