Claim: Friendship has been studied in academic fields such as sociology.

Friendship is a relationship of mutual affection between people . Friendship is a stronger form of interpersonal bond than an association . Friendship has been studied in academic fields such as communication , sociology , social psychology , anthropology , and philosophy . Various academic theories of friendship have been proposed , including social exchange theory , equity theory , relational dialectics , and attachment styles . A World Happiness Database study found that people with close friendships are happier .   Although there are many forms of friendship , some of which may vary from place to place , certain characteristics are present in many types of bond . Such characteristics include affection ; sympathy ; empathy ; honesty ; altruism ; mutual understanding and compassion ; enjoyment of each other 's company ; trust ; and the ability to be oneself , express one 's feelings , and make mistakes without fear of judgment from the friend .   While there is no practical limit on what types of people can form a friendship , friends tend to share common backgrounds , occupations , or interests and have similar demographics .