The basic components of a puukko are a hilt and a blade along with a sheath, which can be attached to a belt. The blade is short, typically less than 100 mm.
The flat back allows the user to place a thumb or his other hand on it to concentrate the force. Puukkos are used both as a tool for all kinds of carving, especially to work wood, and to clean the catches of anglers and hunters. Some puukko designs have a slightly upwards or downwards curved point, depending on what purpose the knife has. A hunting puukko's tip is often curved downwards to make skinning and opening the animal easier and less messy. The blade is relatively short, usually about the same length as the handle. Fisherman's puukkos sometimes have a small dovetail on point to ease scraping off the innards of a fish.
Most puukkos have a slight shoulder but no choil, since the point where the edge ends and the handle begins is also the point where most power can be applied. A puukko often has no guard to stop the hand from slipping onto the edge, but this is of no great importance, since it is primarily considered a cutting tool, not a stabbing weapon. In cases where the knife and the hand are expected to get wet, like if the puukko is meant for gutting fish or game, some form of guards are carved into the handle. The traditional length of the puukko blade is the same as one's palm width, usually 90–120 mm. Carvers, huntsmen and leatherworkers favour shorter blades; woodworkers, carpenters and constructors longer. The Saami leuku, which is an outdoorsman's tool, may have blade up to 400 mm, and historical väkipuukko up to 500 mm; it is more a machete or short sword (scramasax style) rather than true puukko.
Both factory forged and hand forged blades are often laminated. A thin layer of very hard steel (traditionally crucible steel made from limonite iron) is sandwiched between two layers of softer metal, which make the blade less brittle and facilitates repeated sharpening. Before the 19th century, almost all iron in Finland was made from limonite on charcoal blast furnaces, which yield very pure and high quality iron suitable for crucible steel. German silver steel was and is a popular core-steel material. Today both carbon steel and tool steel are used. The blade can be lightened and strengthened with a fuller.
The traditional material for the handle is birch. Also oak, ash, pine bark, horn (especially elk and reindeer), scrimshaw and bone are used. Often the handle is made from various materials between spacers. Today, however, industrially made puukkos often have plastic handles.
In Finland and northern Scandinavia many men put great pride in carving their puukko's handle. Over generations, this knife has become intimately tied to Nordic culture, and in one or another version is part of many national costumes. A good puukko is equal parts artistic expression and tool. Making it requires a lot of different skills: not only those of a bladesmith, but also those of a carver, a jeweller, a designer, and a leatherworker to make the sheath — and if you master the difficult art of weaving birchbark, this is an opportunity to use it. Finest puukkos have blades of Damascus steel, and forging a blade using blister steel was considered the hallmark of a master smith. As the process of making wootz was rediscovered in Finland in the 1980s, some master smiths have made wootz puukkos.
Men's and women's puukkos do not significantly differ. The only difference is that women's puukkos are often shorter, may have decorated sheaths, and are better suited for working with foodstuffs. Both boy and girl Scouts consider the puukko their scouting symbol as well as a handy tool. Getting a good puukko as a gift or present is considered a great honour in Finland.
In the Nordic countries, the puukko is an "everyday" knife that is used for everything from hunting, fishing, and garden work to opening boxes in the warehouse. Many traditional puukkos are nowadays manufactured in industrial or near-industrial scale by many companies, Marttiini and Iisakki Järvenpää Oy being the most notable. Bearing of sharp objects which could be used as weapons was banned in Finland in 1977. Since then, the puukko has lost its visibility in public places and been restricted to household work, hunting and fishing. In many industries the Mora knife which has a much cheaper construction is in use. The mora knife's handle is typically plastic, and the blade is either stainless steel or of laminated construction; harder steel which forms the edge is clad in softer steel. In Finnish, these knives also are usually referred to as puukko.
In Finland carrying a blade in public spaces without a permit or job related reason is prohibited. Currently, the only urban areas where they can be seen carried openly are garrisons. The puukko is the only civilian item which can be openly worn as a part of a soldier's combat gear without breaching Finnish Army regulations, and most conscripts bring their own puukkos with them into military service. It is a custom of Finnish conscripts, non-commissioned officers, and officer cadets to carry a decorated and engraved commemorative puukko of their year course as a part of their uniform, not unlike a commemorative dagger. This is rationalized as the carrying of a handy tool, but it also doubles as a symbolic sidearm. Puukkos proved to be good close combat weapons in the Winter War and Continuation War. The bayonet of the Rk-62 assault rifle has been designed to also function as a puukko, as was the rare bayonet for the M/39 Mosin-Nagant. Openly carrying a puukko, while technically illegal is not vigorously enforced. Construction workers often go to diners with a puukko hanging from their coveralls and in the rural and Northern parts of the land it is not uncommon to go shopping in the village stores wearing hunting clothes that includes a puukko.
In Finland, receiving a puukko as a gift is considered an honor. The idea behind this is the presenter gives the recipient a tool which is essential for both woodworking, preparing food and as a sidearm, and that the presenter takes into account the well-being of the recipient.
Tapio Wirkkala, famous Finnish designer designed a Puukko for Gutmann cutlery
The puukko has also given the root for Finnish language verb puukottaa, "to stab (with a knife)" or literally "to knife".
The word 'puukko' has gained a modern usage in Finnish computer programming, where it is used synonymously with the English noun 'hack'.
Tommi puukko 
Knife smith Kalle Keränen from Hyrynsalmi in the northern Finland province of Kainuu studied knife making in Fiskars 1867-1868. His teacher was English smith Thomas Woodward from Sheffield. The "Kainuun Puukko" company he founded produced traditional-styled puukko, but with the latest metal-working techniques, and these superior puukko became known as "tommi puukko" - from Thomas Woodward's name.
See also 
|Look up puukko in Wiktionary, the free dictionary.|