Razor be used on both sides, with two open edges. The blade on the double-edged safety razor is slightly curved to allow for a smoother and cleaner shave. In 1901, the American inventor King Camp Gillette, with the assistance of William Nickerson, patented a new variation of safety razor with disposable blades. Gillette realized that a profit could be made by selling an inexpensive razor with disposable blades. This has been called the razor and blades business model, and has become a very common practice for a wide variety of products. Many other brands of safety razors have come and gone.
Safety razor in common use today. Razors commonly include one to five cutting edges. The first step towards a safer-to-use razor was the guard razor – also called a straight safety razor – which added a protective guard to a regular straight razor. The first such razor was most likely invented by a French cutler Jean-Jacques Perret circa 1762. The invention was inspired by the joiner's plane and was essentially a straight razor with its blade surrounded by a wooden sleeve. The earliest razor guards had comb-like teeth and could only be attached to one side of a razor; a reversible guard