U.S. Patent & Trademark Office http://www.uspto.gov
USPTO Search Page https://ppubs.uspto.gov/pubwebapp/static/pages/landing.html
USPTO Classification Page http://www.uspto.gov/web/patents/classification/
European Patent Office Search Page http://worldwide.espacenet.com/
Of the 4 main types of Intellectual Property Protection, Copyright, Trademark, Trade Secret, and Patent, Patent is introduced here.
A Patent is a 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 throught the United states or importing the invention intor the United States" for a limited time in exchange for public disclosure of the invention when the patent is granted.
3 Types of Patents
See http://www.uspto.gov/patents/resources/types/utility.jsp
See http://www.uspto.gov/web/offices/com/iip/pdf/brochure_05.pdf
4 Criteria are
Citations for patents vary depending on the format:
MLA Citation:
Jobs, Steve, et al. "Highly portable media device." Patent 8,993,866. 31 March 2015.
APA Citation:
Jobs, S., et al. (2015). U.S. Patent No. 8,993,866. Washington, DC: U.S.
ACS Citation:
Jobs, S., et al. Highly portable media device. U.S. Patent 8,993,866, 2015.
CSE Citation:
Jobs, S, et al, inventor; 2015 Mar. 31. Highly portable media device. United States patent US 8,993,866.
Chicago Manual of Style:
Jobs, S., et al. Highly portable media device. US Patent 8,993,866, filed August 3, 2012, and issued March 31, 2015 .
See also: http://www.patent-search-information.com/how-to-cite-patent.html