A jigsaw is a special vertical saw used to cut in irregular shapes, notably curves. Jigsaws are now power tools, but were originally manual. (Fretsaws are also called jigsaws.)The expression 'jigsaw puzzle' is better known than the jigsaw itself as a common expression. (Ironically, most modern jigsaw puzzles use stamping to cut out the pieces.) The jigsaw's primary use for other purposes is custom-cutting to specific plans, using either a template or drawn measurements on the subject materials.