Generally, patent information is information on published patent applications, granted patents and registered utility models. Original information comes from the official publications of the national patent offices. Patent information may later be processed to the level where the patent information of different states is collected into one uniform database to provide more convenient access.
The value of the patent information compared to that of other scientific and engineering information is that it contains the quickest access to the newest information about inventions. As a rule, the inventions are kept top secret before the publication of the patent applications.
Patent information is available at the Patent Libraries.
There is also a free online patents database Espacenet.