Desires are states of mind that are expressed by terms like "wanting", "wishing", "longing" or "craving". A great variety of features is commonly associated with desires. They are seen as propositional attitudes towards conceivable states of affairs. They aim to change the world by representing how the world should be, unlike beliefs, which aim to represent how the world actually is. Desires are closely related to agency: they motivate the agent to realize them. For this to be possible, a desire has to be combined with a belief about which action would realize it. Desires present their objects in a favorable light, as something that appears to be good. Their fulfillment is normally experienced as pleasurable in contrast to the negative experience of failing to do so. Conscious desires are usually accompanied by some form of emotional response. While many researchers roughly agree on these general features, there is significant disagreement about how to define desires, i.e. which of these features are essential and which ones are merely accidental. Action-based theories define desires as structures that incline us toward actions. Pleasure-based theories focus on the tendency of desires to cause pleasure when fulfilled. Value-based theories identify desires with attitudes toward values, like judging or having an appearance that something is good.

Desires can be grouped into various types according to a few basic distinctions. Intrinsic desires concern what the subject wants for its own sake while instrumental desires are about what the subject wants for the sake of something else. Occurrent desires are either conscious or otherwise causally active, in contrast to standing desires, which exist somewhere in the back of one's mind. Propositional desires are directed at possible states of affairs while object-desires are directly about objects. Various authors distinguish between higher desires associated with spiritual or religious goals and lower desires, which are concerned with bodily or sensory pleasures. Desires play a role in many different fields. There is disagreement whether desires should be understood as practical reasons or whether we can have practical reasons without having a desire to follow them. According to fitting-attitude theories of value, an object is valuable if it is fitting to desire this object or if we ought to desire it. Desire-satisfaction theories of well-being state that a person's well-being is determined by whether that person's desires are satisfied.

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. Techniques include creating a sense of lack in the viewer or associating the product with desirable attributes. Desire plays a key role in art. The theme of desire is at the core of romance novels, which often create drama by showing cases where human desire is impeded by social conventions, class, or cultural barriers. Melodrama films use plots that appeal to the heightened emotions of the audience by showing "crises of human emotion, failed romance or friendship", in which desire is thwarted or unrequited.