Evidence of Use (EoU) is a sort of analysis used to defend patent holders’ and investors’ intellectual property and related interests. The comprehensive mapping technique used in creation of EoU chart maps each element of the patent claim(s) to the infringing (accused) product or a standard.

There are two types of EoU charts:

• Patent-to-Product Mapping: a process of mapping a patent and one or more of its claims to a specific product or a specific component, part, feature, or function within that product. It is used to determine how closely the product matches the claim.
• Patent-to-Standard Mapping: The mapping of a patent to the relevant sections of a standard proves patent infringement by products that comply with the mapped standard.

For patent portfolio managers, patent practitioners, and individual inventors, EoU is regarded as one of the most important services. It is the first stage in determining whether or not to pursue patent litigation or licencing with possible partners.