Government Information: Federal, State & Local: Patents/Trademarks
U.S. Patent and Trademark Office (USPTO)
Search issued patents, patent applications, and trademarks.
Guides to Searching
General Information Concerning Patents - see especially "What is a Patent?"
The 7-step strategy - the search process described is complex, recommended for professional patent searchers
How do I use the U.S. Patent Classification Site? - explains searching by Classification numbers
How to Access Full-page Images. How to view and print full text patent images including drawings.
Tips on Fielded Searching - probably the most useful guide for the novice patent searcher, since searching within fields (sections) is easy to understand and results in precise, although not comprehensive, searches
Manual of Classification - guide to the classification schedule used to classify patents and patent applications; searchable by class, subclass, and keyword
USPC Index - browsable index to the entire US Patent Classification