A trademark is made up of any word, name, symbol, or device, or combination thereof, adopted and used by a manufacturer or merchant to identify its products and to differentiate them from those manufactured or sold by others. Trademarks are an important form of intellectual property protection for companies, as they serve as the legal foundation for brands. While the definition of a “brand” is similar to a trademark (“name, term, design, symbol, or any feature that identifies one seller's good or service as distinct from those of other sellers”), the concept of brand is more encompassing than its legal foundation. Although brands distinguish goods “so as to source,” they also serve as promises to consumers. Marketers talk about brands as market-based sources of firm equity, and as strategic assets. Marketers also talk of brands as having personalities, as sources of emotional attachment, and as entities around which consumers form communities. So while brands find their legal foundation in trademarks, they possess values to organizations that have never been protected under trademark law, because a brand's equity extends far beyond a firms’ ability to reduce consumer confusion.
Legal protection of trademarks in the United States grew out of the common law concept of “passing off” as a form of unfair competition, through the copying of products. Historically, trademark protection was intended to prevent confusion among consumers by ensuring that they were able to distinguish among different competitors, and so that they could identify particular products with particular craftsmen and manufacturers. Trademarks benefit consumers, and by extension producers, by eliminating confusion in two ways. First, trademarks serve as indicators of quality to consumers, since the ability to tie a product to a source enhances the likelihood that a firm will stand behind its product. Second, trademarks allow firms to differentiate their products from competitor products, creating variety and assortment, to the benefit of heterogeneous segments of consumers. Trademark protection, like copyright and patent protection, serves as an incentive for firms to produce products of the highest quality, to the benefit of consumers. In the USA the primary mechanism for trademark protection today is section 43(a) of the Lanham Act of 1946, as it has been interpreted by the United States Supreme Court.