A dirk is a type of dagger, a small, sturdy knife which can be easily carried by a variety of people. Many people associate dirks particularly with Scotland, due to the highly evolved dirk which emerged in Scotland around the 18th century. Other cultures also carried dirks; Naval dirks were worn until the early 20th century, for example, and pirates used a shorter version of the traditional dirk. In general, the term refers loosely to any sort of long, straight bladed, double sided knife; due to their length, the carrying of dirks is often restricted in the legal codes of many nations.
The basic form of the dirk appears to have emerged at some point during the Bronze Age. The straight blade would have been easy to forge and sharpen, and the knives made very useful multitools. In addition to being used in battle, dirks could cut food, trim rope or hide, and function in a variety of other tasks. Dirks have traditionally been shorter than swords, making them easier to wield and less costly, meaning that people of lower classes could carry dirks when they could not afford swords.
People who could afford swords often carried dirks as well, as backup weapons. The length of a dirk could vary; generally the blade was at least longer than the hand, and sometimes much longer. The handle of a dirk is designed to provide some protection to the wearer's hand without being unwieldy; some dirks are also designed for throwing, with carefully balanced blades to promote straight, even flight.
In Scottish culture, the dirk or durk was an important part of traditional dress for men of all ages. Scottish men were rarely found without their dirks, which were typically worn sheathed at the belt. After a series of Scottish insurrections against the English, the wearing of dirks and other forms of traditional Scottish dress like Tartans was forbidden; the traditional knife became a politically charged object, and some Scots wore it anyway as a symbol of rebellion.
Many companies make replicas of traditional dirks; these replicas are available in varying qualities. In some cases these knives are poor facsimiles which are designed to be used as props, not as true daggers. A few knife manufacturers make durable, high quality dirks which are on-par with their historical counterparts, although they can be costly and difficult to track down. As with all bladed weapons, it is an excellent idea to check on prevailing local codes before wearing a dirk, to ensure that you comply with the law, if you wish to avoid arrest and confiscation of your knife.