A Practice Note discussing the Lanham Act's requirement that trademarks be used in US commerce to be protectable. It addresses the factors that courts and the US Patent and Trademark Office (USPTO) consider when determining whether use of a mark or name is sufficient to support federal registration or unregistered trademark rights under common law. This Note also addresses relevant considerations when assessing which party in litigation or a Trademark Trial and Appeal Board (TTAB) proceeding has superior or prior trademark rights.