We’ve all noticed the “WC” sign on public restrooms, but do we know what it stands for?

There are many questions in life that often go unanswered—like where do missing socks go or why pizzas come in square boxes.

But today, let’s finally answer a common curiosity: what does “WC” really mean?

While most of us use common abbreviations like LOL and WTF, some can be trickier to understand. Take “WC,” for instance, which appears on restroom doors.

Though we often call it a “bathroom” or “restroom,” “WC” stands for “water closet.” This term dates back to the advent of indoor plumbing, when people needed a dedicated space for their new toilets.

TikToker Nathan (@itsnathannyc) recently explained it in a video: “Oh, you sweet young thing! WC stands for ‘water closet’.”