A patent is a set of exclusive rights granted by the government to an inventor for his invention for a certain amount of time. It provides the inventor with exclusive rights to his invention and excludes others from manufacturing the item for a certain time period. This process includes paperwork that the inventor submits which details his invention, including its usefulness. For a quick explanation of patents, check out Wikipedia at http://en.wikipedia.org/wiki/Patent.
A good overview of U. S. patent history and research can be found at the web site for the PBS TV show History Detectives at http://www.pbs.org/opb/historydetectives/techniques/patent.html. The web site also includes some helpful links to aid in your research.
One way to search for a patent is by talking to a librarian at a U.S. Patent and Trademark Library. According to the Patent Office's web site, a Depository Library receives copies of patents and trademark materials, then makes them and information about patents available to the public. For a list of these libraries, organized by state, go to http://www.uspto.gov/go/ptdl/ptdlib_1.html
Through the U.S. Patent and Trademark Office, Uspto Web Patent Databases, patents issued from 1790 to 1975 are searchable only by patent number, issue date, and current U.S. classification. The web site states that if you try to search using any other method you will receive an error message. According to the web site, "patents issued after January 1976 offers full searchable text, including all bibliographic data such as the inventor's name, the patent title, assignee's name, abstract, the full description of the invention, and the claims.
Free Patents Online, http://www.freepatentsonline.com/,claims to have more complete information than is found on the U.S. Patent and Trademark Office. For a list of the patents it has online see the web page at http://www.freepatentsonline.com/help/item/What-data-does-this-site-have.html.
The Wyoming Inventors Database, Wyoming Inventors Database, provides a searchable database by surname for patents where at least one of the inventors was from Wyoming. After a search of the index by surname, you will be rewarded with a listing of matches that include the name of the invention, the inventor's name, issue date and patent number. A link is provided to the U.S. Patent Office where you can look at the patent documentation.
Foreign Patents are also searchable on the Web. For Canadian patents see the Canadian Intellectual Properties Office at http://patents.ic.gc.ca/cipo/cpd/en/introduction.html. This online database is for patents issued in the last 75 years. Delphion has searches for patents for Europe and Japan at http://www.delphion.com/simple. This is a subscription site and requires a fee. The European Patent Office can be found at http://ep.espacenet.com/.