Friendship is a term used to denote co-operative and supportive behavior between two or more humans. This article focuses on the notion specific to interpersonal relationships. In this sense, the term connotes a relationship which involves mutual knowledge, esteem, and affection along with a degree of rendering service to friends in times of need or crisis. Friends will welcome each other's company and exhibit loyalty towards each other, often to the point of altruism. Their tastes will usually be similar and may converge, and they will share enjoyable activities. They will also engage in mutually helping behavior, such as exchange of advice and the sharing of hardship. A friend is someone who may often demonstrate reciprocating and reflective behaviors. Yet for many, friendship is nothing more than the trust that someone or something will not harm them. Value that is found in friendships is often the result of a friend demonstrating on a consistent basis:

* the tendency to desire what is best for the other,
* sympathy and empathy,
* honesty, perhaps in situations where it may be difficult for others to speak the truth, especially in terms of pointing out the perceived faults of one's counterpart
* mutual understanding.
n a comparison of personal relationships, friendship is considered to be closer than association, although there is a range of degrees of intimacy in both friendships and associations. Friendship and association can be thought of as spanning across the same continuum. The study of friendship is included in sociology, anthropology, philosophy, and zoology. Various theories of friendship have been proposed, among which are social psychology, social exchange theory, equity theory, relational dialectics, and attachment styles. See Interpersonal relationships

Friendship is considered one of the central human experiences, and has been sanctified by all major religions. The Epic of Gilgamesh, a Babylonian poem that is among the earliest known literary works in history, chronicles in great depth the friendship between Gilgamesh and Enkidu. The Greco-Roman had, as a paramount example, the friendship of Orestes and Pylades. The Abrahamic faiths have the story of David and Jonathan. Friendship played an important role in German Romanticism. A good example for this is Schiller's Die Bürgschaft. The Christian Gospels state that Jesus Christ declared, "No one has greater love than this, to lay down one's life for one's friends."

In philosophy, Aristotle is known for his discussion (in the Nicomachean Ethics) of philia, which is usually (somewhat misleadingly) translated as "friendship," and certainly includes friendship, though is a much broader concept.

Cultural variations: (stub-section) A group of friends consists of two or more people who are in a mutually pleasing relationship engendering a sentiment of camaraderie, exclusivity, and mutual trust. There are varying degrees of "closeness" between friends. Hence, some people choose to differentiate and categorize friendships based on this sentiment.

Imaginary friend
imaginary friend, also known as "imaginary companions", are pretend characters often created by children. Imaginary friends often function as tutelaries (or perform a tutelary function) when they are engaged by the child in play activity[citation needed]. Imaginary friends may exist for the child into adolescence and sometimes adulthood. Imaginary friends often have elaborate personalities and behaviors. Although they may seem very real to their creators, studies have shown that children understand that their imaginary friends are not real.
Medical and philosophical aspects

The development of imaginary friends by a person does not alone necessarily signify a problem or disorder.[2][3] According to the DSM-IV, imaginary friends are classified as a psychological disorder only if they interfere with everyday social interactions[citation needed]. It could possibly be a solution to feeling lonely.

According to some theories of psychology[citation needed], an understanding of a child's conversations with their imaginary friends can reveal a lot about the anxieties and fears of that child as well as the child's aspirations and perception of the world. Some children report that their "imaginary friends" manifest themselves physically, and are indistinguishable from "real" people.

Purposes
People may invent imaginary friends for companionship, as part of play, or for other reasons. Imaginary friends can serve as an important source of companionship to some children and adults. As an example, clinical psychologists have reported that[citation needed] young children in boarding schools often develop imaginary friends to cope with extreme stress and separation from their family.

According to some psychological theories[citation needed], children often use their imaginary friends as outlets for expressing desires which they would normally be afraid to engage in or for which they would normally be punished. Proponents of these theories state[4] that it is not uncommon for a child to engage in mischief or wrong-doing and then to blame the crime on their imaginary friend, allowing the child to act out fantasies that they are otherwise restricted from experiencing due to societal constraints. Similarly, psychologists report[citation needed] that children often give their imaginary friends personality traits that they themselves lack and make their imaginary friends into ideal versions of themselves: shy children often describe their imaginary friends as playful and outgoing jokesters who are always making them laugh and who are very popular.

A long-time popular misconception holds that most children dismiss or forget the imaginary friend once they begin school and acquire 'real' friends. Some psychologists have suggested that children simply retain but stop speaking about imaginary friends, due to adult expectations and peer pressure. Some children report creating or maintaining imaginary friends as preteens or teenagers[citation needed], and a very few adults report having imaginary friends. This may, however, signal a serious psychological disorder.