A drawstring is a cord or string threaded through fabric that you can pull to tighten or close an opening. When you pull both ends of a drawstring, the fabric gathers and cinches tight, like pulling the strings on a bag to keep your gym clothes from falling out.

You'll find drawstrings in lots of everyday items. The waistband of your sweatpants probably has a drawstring you can adjust to keep them from slipping down. A drawstring backpack closes when you pull the cords at the top. Hoodies often have drawstrings around the hood that let you tighten it against cold wind or rain.

The clever part about drawstrings is how simple they are: just a cord running through a fabric tube or channel, called a casing. Pull the cord, and the fabric bunches up. Loosen it, and the opening widens again. This makes drawstrings perfect for things that need adjustable openings, whether you're cinching a laundry bag, closing a gift pouch, or keeping your pajama pants from sliding down while you sleep. People have been using drawstrings for hundreds of years because the design works so well and requires no buttons, zippers, or complicated mechanisms.