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 antecedent 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.