A trade name, trading name, or business name is a pseudonym used by companies to perform their business under a name that differs from the registered, legal name of the business. Trade names are typically used by companies to conduct their operations under a simpler brand as opposed to using their formal name within all public communications, or when a desired name was not able to be registered by the business operator, or if that business is owned by a separate company, franchisee, or a sole proprietorship. Trade names are also used in drug nomenclature with specific policies and guidelines for use in academic publications, (for example, atorvastatin (trade name Lipitor by Pfizer)).