Patent claim

In a patent or patent application, the claims define in technical terms the extent, i.e. the scope, of the protection conferred by a patent, or the protection sought in a patent application. In other words, the purpose of the claims is to define which subject-matter is protected by the patent (or sought to be protected by the patent application). This is termed as the "notice function" of a patent claim—to warn others of what they must not do if they are to avoid infringement liability. The claims are of paramount importance in both prosecution and litigation.

For instance, a claim could read:

• "An apparatus for catching mice, said apparatus comprising a base, a spring member coupled to the base, and ..."
• "A chemical composition for cleaning windows, said composition substantially consisting of 10–15% ammonia, ..."
• "Method for computing future life expectancies, said method comprising gathering data including X, Y, Z, analyzing the data, comparing the analyzed data results..."