The Scientist by Mikiko Ponczeck.
International patent blog from Wolters Kluwer.
No patent system is an island, alone unto itself. Patent researchers in the U.S. have to take into account patent systems--and databases--in other regions and even individual countries. Why? Well, for one reason, international treaties bind the world together on this topic. The Patent Cooperation Treaty, for instance, allows an international application filed with the USPTO to designated for filing in national patent offices of signatory countries. For another, prior art can consist of inventions patented somewhere else. So a prior art search should include foreign databases as well. Even if you don't know any foreign languages, the international databases and websites usually have resources in English and are fairly easy to navigate.
International cooperation on patents seems like it should be a recent phenomenon, perhaps even younger than other efforts of international agreement like the United Nations. This is not the case. Thirty years before countries were engaged in the most monumental conflict the world had yet seen, many of the opponents in that struggle reached agreement on the protection of industrial property in general and patents in particular. This consensus was the Paris Treaty of 1883 (ratified by the U.S. in 1887). This was followed over the subsequent decades by additional conventions intended to harmonize the application and protection of patents world wide.
Below is a selective list of intergovernmental and governmental patent offices with sigificant patent business. Web links to most patent offices can be found at WIPO's directory of intellectual property offices.
Below is a sampling of patent databases offered by organizations and countries throughout the world.
Patent classications organize the body of inventive knowledge into a searchable index. With patents assigned classification numbers or headings, researchers can hone ino on their target, supplementing a terms and connectors search to come up with a better result.
While patent laws are fairly uniform throughout the world, there are still significant differences between various countries. These secondary sources will point out these variations. Some are even dedicated to a specific country.