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A can opener (in North American English and Australian English) or tin opener (in British and Commonwealth English) is a device used to open tin cans (metal cans). Although preservation of food using tin cans had been practiced since at least 1772 in the Netherlands, the first can openers were not patented until 1855 in England and 1858 in the United States. These early openers were basically variations of a knife, though the 1855 design continues to be produced. The first can opener consisting of the now familiar sharp rotating cutting wheel was invented in 1870 but was considered too difficult to operate for the ordinary consumer. A breakthrough design came in 1925 when a second, serrated wheel was added to hold the cutting wheel on the ring of the can. This easy to use design has become one of the most popular can opener models.

Around the time of World War II, several can openers were developed for military use, such as the American P-38 and P-51. These featured a robust and simple design where a folding cutting blade and absence of a handle significantly reduced the opener size. Electric can openers were introduced in the late 1950s and met with success. The development of new can opener types continues with the recent addition of a side-cutting model.

Food preserved in tin cans was in use by the Dutch Navy from at least 1772. Before 1800, there was already a small industry of canned salmon in the Netherlands. Freshly caught salmon were cleaned, boiled in brine, smoked and placed in tin-plated iron boxes. This canned salmon was known outside the Netherlands, and in 1797 a British company supplied one of their clients with 13 cans. Preservation of food in tin cans was patented by Peter Durand in 1810. The patent was acquired in 1812 by Bryan Donkin, who had later set up the world's first canning factory in London in 1813. By 1820, canned food was a recognized article in Britain and France and by 1822 in the United States. The first cans were robust containers, which weighed more than the food they contained and required ingenuity to open, using whatever tools available. The instruction on those cans read "Cut round the top near the outer edge with a chisel and hammer." The gap of decades between the invention of the can and can opener may be attributed to the functionality of existing tools versus the cost and effort of a new tool.

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