A patent is an intellectual property right granted by the Government of the United States of America to an inventor "to exclude others from making, using, offering for sale, or selling the invention throughout the United States or importing the invention into the United States" for a limited time in exchange for public disclosure of the invention when the patent is granted.
A patent does not grant the inventor the right to make, use, offer for sell, etc. only the right to exclude others from doing so. U.S. patents are effective only within the United States. The federal government does not enforce a patent that is responsible of the patentee.
There are three types of U.S. patents: Utility, Design, and Plant. Utility Patents cover new and useful processes, machines, articles of manufacture, composition of matter, or any new and useful improvement to any of the above. Design patents cover new, original, and ornamental design for an article of manufacture, and finally Plant Patents cover distinct and new varieties of a plant. In the United States patents are granted by the federal government and governed by federal law. Since 1985, Utility and Plant Patents are granted for a term which begins with the date of the grant and usually ends 20 years from the date of application subject to the payment of appropriate maintenance fees, while Design Patents last 14 years from the date granted.
Besides the United States, other nations also grant patents, and while the types are similar, there are some very marked differences in the protection granted, the processes, etc. One of the most notable is in what constitutes "new".
US Patents Searching. (U.S. Patent and Trademark Office)
Espacenet Patent Search. (European Patent Office) International Patent Searching. Begin by selecting a gateway country.
Google Patents. Search and read full text of patents from around the world. Coverage varies from country to country. Translations provided when necessary.
Patent Lens. (Cambia) Patents from all developed countries and many developing countries. Includes PDFs of most patents.
Patent Searching. (irossco.com) Links to free databases for patent searching. Be careful using any the databases listed since some of the listings allow “free searching” for a limited amount of time, than become subscription based, but still a very useful list.
US Patent Application
EFS - Web. US Patent Application Web site
Design Patent Application Guide
Nonprovisional (Utility) Patent Appication Filing Guide
Plant Patent Application Guide
International Patent Application
PCT (Patent Cooperation Treaty) Application (concurrent application in up to 143 countries)
Patent. (Cornell University Law School. Legal Information Institute)
Patent it yourself: your step-by-step guide to filing at the U.S. Patent Office. David Pressman. Berkeley, California: Nolo, 2012. Also check public libraries in your area for this title.
Patent Searching. (University of Minnesota. University of Minnesota Libraries) Tutorial on Searching Google Patents and USPTO.
Patents. (United States Patent and Trademark Office)
Patents, Copyright and Intellectual Property. (University of Chicago. University of Chicago Libraries) Some of the links are dated, but the overall information is still good.