Love is any of a number of emotions and experiences related to a sense of strong affection or profound oneness. Depending on context, love can have a wide variety of intended meanings. It is commonly conceived of romantically, as a deep, ineffable feeling of intense and tender attraction shared in passionate or intimate interpersonal and sexual relationships. Love can also be conceived of as Platonic love, religious love, familial love, and, more casually, anything considered strongly pleasurable, desirable, or preferred, including activities and foods.This diverse range of meanings in the singular word love is often contrasted with the plurality of Greek words for love, reflecting the concept's depth, versatility, and complexity.
The definition of love is the subject of considerable debate, enduring speculation, and thoughtful introspection. In ordinary use, love usually refers to interpersonal love, an experience felt by a person for another person. Love often involves caring for or identifying with a person or thing, including oneself (cf. narcissism). Dictionaries tend to define love as deep affection or fondness. In colloquial use, according to polled opinion, the most favored definitions of love involve altruism, selflessness, friendship, union, family, and bonding or connecting with another.
The different aspects of love can be roughly illustrated by comparing their corollaries and opposites. As a general expression of positive sentiment (a stronger form of like), love is commonly contrasted with hate (or neutral apathy); as a less sexual and more mutual and "pure" form of romantic attachment, love is commonly contrasted with lust; and as an interpersonal relationship with romantic overtones, love is commonly contrasted with friendship, although other connotations of love may be applied to close friendships as well.
The very existence of love is sometimes subject to debate. Some categorically reject the notion as false or meaningless. Others call it a recently-invented abstraction, sometimes dating the "invention" to courtly Europe during or after the Middle Ages.
Cultural differences make any universal definition of love difficult to establish. Expressions of love may include the love for a soul or mind, the love of laws and organizations, love for a body, love for nature, love of food, love of money, love for learning, love of power, love of fame, love for the respect of others, etc. Different people place varying degrees of importance on the kinds of love they receive. Love is essentially an abstract concept, easier to experience than to explain. Because of the complex and abstract nature of love, discourse on love is commonly reduced to a thought-terminating cliché, and there are a number of common proverbs regarding love, from Virgil's "Love conquers all" to The Beatles' "All you need is love".
Biological models of sex tend to view love as a mammalian drive, much like hunger or thirst. Helen Fisher, a leading expert in the topic of love, divides the experience of love into three partly-overlapping stages: lust, attraction, and attachment.
Lust is the initial passionate sexual desire that promotes mating, and involves the increased release of chemicals such as testosterone and estrogen. These effects rarely last more than a few weeks or months. Attraction is the more individualized and romantic desire for a specific candidate for mating, which develops out of lust as commitment to an individual mate forms. Recent studies in neuroscience have indicated that as people fall in love, the brain consistently releases a certain set of chemicals, including dopamine, norepinephrine, and serotonin, which act similar to amphetamines, stimulating the brain's pleasure center and leading to side-effects such as an increased heart rate, loss of appetite and sleep, and an intense feeling of excitement. Research has indicated that this stage generally lasts from one and a half to three years.
Since the lust and attraction stages are both considered temporary, a third stage is needed to account for long-term relationships. Attachment is the bonding which promotes relationships that last for many years, and even decades. Attachment is generally based on commitments such as marriage and children, or on mutual friendship based on things like shared interests. It has been linked to higher levels of the chemicals oxytocin and vasopressin than short-term relationships have.
Further information: Human bonding
Following developments in electrical theories, such as Coulomb's law, which showed that positive and negative charges attract, analogs in human life were developed, such as "opposites attract". Over the last century, research on the nature of human mating, such as in evolutionary psychology, agree that pairs unite or attract to each other owing to a combination of opposites attract, e.g. people with dissimilar immune systems tend to attract, and likes attract, such as similarities of personality, character, views, etc. In recent years, various human bonding theories have been developed described in terms of attachments, ties, bonds, and or affinities.
Some Western authorities disaggregate into two main components, the altruistic and the narcissistic. This view is represented in the works of Scott Peck, whose works in the field of applied psychology explored the definitions of love and evil. Peck maintains that love is a combination of the"'concern for the spiritual growth of another", and simple narcissism. In combination, love is an activity, not simply a feeling.