What is prior art

Usually when people talk about prior art, they mean those patents which have been registered in patent offices and which are related to their project of interest. Because the patents registered in USPTO, EPO, PCT, and JPO covers more than 90% of patents filed worldwide, a prior art search is usually a search for patents that have been registered in those patent offices.

Generally, a patent attorney compares the prior art to a proposed idea/design to determine whether the proposed idea/design is patentable.

However, in a wider scope, a prior art also includes any related information in journals, magazines, newspapers, internet (public domain) in addition to the registered patents in patent offices.

Japanese patent information is a prime source for prior art because of the volume of documents stored at Japan patent office. While Japanese patent information is every important, it is very difficult to search these documents.