Desire is a sense of longing or hoping for a person, object, or outcome. The same sense is expressed by emotions such as "craving." When a person desires something or someone, their sense of longing is excited by the enjoyment or the thought of the item or person, and they want to take actions to obtain their goal. The motivational aspect of desire has long been noted by philosophers; Thomas Hobbes (1588–1679) asserted that human desire is the fundamental motivation of all human action. While desires are often classified as emotions by laypersons, psychologists often describe desires as different from emotions; psychologists tend to argue that desires arise from bodily structures, such as the stomach's need for food, whereas emotions arise from a person's mental state. Marketing and advertising companies have used psychological research on how desire is stimulated to find more effective ways to induce consumers into buying a given product or service. While some advertising attempts to give buyers a sense of lack or wanting, other types of advertising create desire associating the product with desirable attributes, by showing either a celebrity or a model with the product.