Only individuals who made an inventive contribution to the subject matter claimed in the patent application are considered inventors. Individuals who have made other contributions, such as gathering essential data or constructing a practical embodiment of the invention, are not inventors unless they also made an inventive contribution. Similarly, a project supervisor is not entitled to inventor status simply because of his or her supervisory role; an inventive contribution is the singular criterion. The claims of the patent application legally determine who is and who is not an inventor. The patent claims should be used as a guideline for determining inventorship. For this reason, inventorship can change during prosecution of the patent application, as the claims are amended. Accurately identifying all the inventor(s) is a prerequisite for a valid U.S. patent.