A viral social media post recently highlighted a common curiosity: what is the raised line found on many bath towels? Online users jokingly called it a “face-to-butt separator” or a towel’s “racing stripe,” but the real reason is practical, not humorous.

That line is known as a “dobby border.” Though it may appear decorative, it plays an important role in how towels are made and used. Textile experts explain that it helps towels “hold their shape and last longer,” especially after repeated washing.

One key purpose of the dobby border is reinforcement. It strengthens the towel’s edges and helps prevent fraying, which is important for items that are washed and used frequently. This added durability extends the towel’s lifespan.

The border also helps control thickness at the ends of the towel. By preventing bulkiness, it allows towels to “fold neatly” and remain soft and easy to handle, without interfering with absorbency.

Finally, the dobby border offers a subtle space for design. Manufacturers may add patterns or logos there without affecting comfort. While often overlooked, this small detail helps towels “look good, feel better, and last longer.”