Trademark Electronic Search System.
USPTO's online database for searching pending, registered and dead federal trademarks. TESS is free and intended for use by the general public. Due to limitations of equipment and bandwidth, TESS is not intended to be a source for bulk downloads of USPTO data. Bulk data may be purchased from USPTO at cost (see the USPTO Products and Services Catalog). Individuals, companies, IP addresses, or blocks of IP addresses who, in effect, deny service to the general public by generating unusually high numbers of daily TESS accesses (searches, pages, or hits), whether generated manually or in an automated fashion, may be denied access to these servers without notice.
Source: U.S. Patent and Trademark Office.