To receive a U.S. patent, an invention must be considered new, useful, and non-obvious. You cannot patent inventions that are already widely used or described, that have no useful purpose, or that would be obvious to anyone with ordinary skill in that art.

There are three kinds of patents in the United States: Utility patents cover any new and useful process, machine, article of manufacture, or composition of matter. They also include improvements on these things.

Design patents cover the new, original and ornamental design of an article of manufacture.

Plant patents are given to someone who invents or discovers and asexually reproduces a new variety of plant.

The first U.S. patent was issued on July 31, 1790 to Samuel Hopkins of Philadelphia. Hopkins discovered a new method for producing potash. Potash was an essential ingredient for making soap, glass and gunpowder.

James Henry Atkinson invented the classic snapping mousetrap that we are all familiar with, called the “Little Nipper,” in 1897. In 1913, Atkinson sold his patent to Procter, the company that has manufactured the “Little Nipper” ever since.

English chemist Humphry Davy invented the first electric arc light in 1809. Canadians Henry Woodward and Matthew Evans patented an electric lightbulb in 1875. Thomas Edison purchased half interest in the patent from the inventors. By 1879, Edison developed an improved carbon filament and in 1885 purchased the full patent.

Edward Hammer, a scientist working for General Electric, designed the compact fluorescent bulb in 1976.

The famous author Mark Twain, who wrote Huckleberry Finn and Tom Sawyer, was also an inventor. In 1871, he received a patent for improving adjustable and detachable straps for clothing. His goal was to do away with suspenders, which he considered uncomfortable. The following year he patented a self-pasting scrapbook.