A patent is a government document that proves that an invention is yours and yours alone. In the U.S., as of 2009, over 7,000,000 patents were issued by the Patent and Trademark Office.
Patent also refers to leather that has a very shiny finish. The process for making leather look like this was once patented, but since patents do not last forever, the process is now available for anyone to use. As with patent leather, the word is often used as part of a sales pitch, explaining why something is special: "We use patented technology..." or "Our patented method..."