A utility knife is a knife used for general or utility purposes. The utility knife was originally a fixed blade knife with a cutting edge suitable for general work such as cutting hides and cordage, scraping hides, butchering animals, cleaning fish, and other tasks.

Today, the term "utility knife" also includes small folding or retractable-blade knives suited for use in the modern workplace or in the construction industry.

The fixed-blade utility knife was developed some 500,000 years ago, when humans began to make knives made of stone. These knives were general-purpose tools, designed for cutting and shaping wooden implements, scraping hides, preparing food, and for other utilitarian purposes.

By the 19th century the fixed-blade utility knife had evolved into a steel-bladed outdoors field knife capable of butchering or cleaning wild game, shaving or notching wood, preparing campfires, opening tins or cans, and preparing meals. With the invention of the backspring, pocket-size utility knives were introduced with folding blades and other folding tools designed to increase the utility of the overall design. These folding pocket utility knives were widely purchased by civilians and increasingly by military forces for issue to individuals soldiers or sailors. The folding pocketknife and utility tool is typified by the Camper or Boy Scout pocketknife, the U.S. folding utility knife, the Swiss Army Knife, and by certain multi-tools fitted with knife blades. The development of stronger locking blade mechanisms for folding knives such as the Spanish navaja, the Opinel, and the Buck 110 Folding Hunter significantly increased the utility of such knives when employed for heavy-duty tasks such as preparing game or cutting through dense or tough materials.

Iain Sinclair FRSL (born 11 June 1943 in Cardiff, Wales) is a British writer and filmmaker. Much of his work is rooted in London, most recently within the influences of psychogeography.

Sinclair was educated at Trinity College, Dublin (where he edited Icarus). He attended the Courtauld Institute of Art (University of London), and the London School of Film Technique (now the London Film School).

His early work was mostly poetry, much of it published by his own small press, Albion Village Press. He was (and remains) closely connected with the British avantgarde poetry scene of the 1960s and 1970s – authors such as J.H. Prynne, Douglas Oliver, Peter Ackroyd and Brian Catling are often quoted in his work and even turn up in fictionalized form as characters; later on, taking over from John Muckle, Sinclair edited the Paladin Poetry Series and, in 1996, the Picador anthology Conductors of Chaos.

His early books Lud Heat (1975) and Suicide Bridge (1979) were a mixture of essay, fiction and poetry; they were followed by White Chappell, Scarlet Tracings (1987), a novel juxtaposing the tale of a disreputable band of bookdealers on the hunt for a priceless copy of Arthur Conan Doyle's A Study in Scarlet and the Jack the Ripper murders (here attributed to the physician William Gull).