A pleat is a fold in fabric that's pressed, stitched, or sewn in place to create a neat crease. Picture a school uniform skirt with those crisp, parallel folds running from the waistband down: those are pleats. They let the fabric hang smoothly at the top but provide extra room to move at the bottom.

Pleats serve both practical and decorative purposes. On a shirt, pleated panels near the shoulders give you room to swing your arms freely. On curtains, pleats create an elegant, gathered look instead of hanging flat. Scottish kilts feature distinctive pleats that wrap around the body, holding yards of tartan fabric in an organized pattern.

Tailors create pleats by carefully folding fabric at precise measurements, then using an iron or stitching to make sure the folds stay put. A pleated skirt might have knife pleats (all folded in one direction), box pleats (folded to create raised panels), or accordion pleats (folded back and forth like the musical instrument). When you see fabric with crisp, evenly spaced folds, you're looking at pleating.