'Friendship' is a term used to denote co-operative and supportive behavior between two or more beings. In this sense, the term connotes a relationship which involves mutual knowledge, esteem, and affection and respect 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 the following 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.

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."(John 15:13).

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.

Rome

During the time of the Roman Empire, Cicero had his own beliefs on friendship. Cicero believed that in order to have a true friendship with someone there must be all honesty and truth. If there isn't, then this isn't a true friendship. In that case, friends must be one hundred percent honest with each other and put one hundred percent of their trust in the other person. Cicero also believed that for people to be friends with another person, they must do things without the expectation that their friend will have to repay them. He also believes that if a friend is about to do something wrong, and something that goes against your morals, you shouldn't compromise your morals. You must explain why what they are going to do is wrong, and help them to see what the right thing to do is, because Cicero believes that ignorance is the cause of evil. Finally the last thing that Cicero believed was that the reason that a friendship comes to an end is because one person in that friendship has become bad. (On Friendship, Cicero)