A pocket knife is a knife with a folding blade which is designed to be small enough to slip into a pocket. Many companies make pocket knives with multiple blades, ensuring that their products will be versatile. A good pocket knife can be an extremely useful tool in a wide range of situations, and they are common equipment for campers, farmers, and emergency services personnel among others. The Swiss Army Knife is probably the most well known brand of pocket knife, with a distinctive logo in the shape of a square cross.
Pocket knives have been popular items for quite some time, with various refinements to the design being introduced over the ages. The pen knife, for example, was carried by gentlemen in the 19th century for the purpose of sharpening the quills of pens, while larger blades were carried by stockmen and explorers in the American West for an assortment of purposes. By 1900, the locking blade had been introduced, making pocket knives much safer since the blades would not snap shut under pressure, and manufacturers started adding useful features to their pocketknives.
A very basic pocket knife may only have have one blade, which is typically straight and long so that it can be used for a variety of functions. Optional additional blades might include things like an awl for drilling through material such as leather, a hooked blade with a smooth outside edge and a sharp inner edge, or corkscrews for opening wine. Pocketknives also come with things like tweezers, toothpicks, small scissors, screwdrivers, and so forth.
With the multitude of options, it can be hard to strike the balance between a pocket knife and a multifunction tool. Ideally, a pocket knife should fit easily in someone's pocket, without obviously bulging. However, many companies make knives which are so loaded with options that they are no longer practical for the pocket, although they can be carried in lightweight tool kits or worn on the belt.
Some people like to give pocket knives as gifts, especially to people who are embarking on trips or new chapters in their lives. Others may pass down these blades as heirlooms, since many manufacturers make very sturdy, solid pocket knives which can be used through multiple generations. A pocket knife is certainly a gift to consider for a new graduate, someone planning a major outdoor expedition, or someone going into a field like emergency services, farming, or forestry.