Google Patents is a search engine from Google that indexes patents and patent applications from the United States Patent and Trademark Office (USPTO), European Patent Office (EPO), and World Intellectual Property Organization (WIPO). These documents include the entire collection of granted patents and published patent applications from each database (which belong to the public domain). US patent documents date back to 1790, EPO and WIPO to 1978. All 8 million patents have been put in the database. Optical character recognition (OCR) has been performed on the pages to make them searchable. This searchability includes all US patents and published patent applications.