The U.S. Patent & Trademark Office (USPTO) Patent Database includes full text of patents from 1790 - present and also provides TIFF images of most of them.
By Patent Number
By Subject
OR ...
You can use the same method of searching in other patent databases on the web. See the Patent Websites tab in this guide for more databases.
See this excellent tutorial from the US Patent and Trademark Office on the patent search process.
This is a helpful guide from the USPTO which uses their 7 Step Strategy with new CPC code system.
The European Patent Office maintains a free database of worldwide patents (including U.S. patents) called Espacenet. Images of patents are provided in PDF format, but can only be printed one page at a time.
By Patent Number
By Subject
Espacenet Tutorial - How to search esp@cenet, the European Patent Office's online patent database
See the Patent Websites tab for additional international patent databases.
Chemical Abstracts Service (CAS) indexes chemical patents from approximately 25 countries and patent organizations. UCSD affiliates may search the online CAS database, Scifinder.
Once you have obtained access to SciFinder Scholar, go to Explore References. To search by patent number, assignee name or inventor name, select Patent and enter the informatio you have. To search by subject, select Research Topic and limit to document type Patent.