Standard-essential patent

Definition
A standard-essential patent (also called an essential patent) is a patent that claims an invention that must be used to comply with a technical standard. Standards organizations, therefore, often require members to disclose and grant licenses to their patents and pending patent applications that cover a standard that the organization is developing. Failure to license an essential patent may be a form of patent misuse.

If a standards organization fails to get licenses to all patents that are essential to complying with a standard, owners of the unlicensed patents may demand or sue for royalties from companies that adopt the standard. This happened to the GIF and JPEG standards, for example.