A pocketknife is a knife with one or more blades that fold into the handle. They are also known as jackknives (jack-knife), folding knives, EDC knife, or may be referred to as a penknife, though a penknife may also be a specific kind of pocketknife. Blade lengths typically range from 5 to 15 centimetres (2 to 6 in). Some pocketknives have multiple tools in addition to one or more blades.

Pocketknives can be used for most of the same purposes as any knife, with the advantage of folding to be carried easily with the blade not dangerously exposed.

Being safely portable, many pocketknives are suitable for use with other tools and equipment for woodcraft and bushcraft.

Specialised designs are used for mushroom hunting and gardening. Pocketknives designed for gardening include pruning knives, which are folding knives with long curved blades used for pruning, trimming cuttings, taking buds and preparing material for grafting.