Friendship is defined as a relationship of mutual affection between two or more living things, and is stronger than a mere association. Two key factors that enable friendship formation are proximity, which allows people to interact, and opportunities to share ideas and feelings. Friendships change over one's life, from sharing toys as children to relationships based on mutual support and understanding as adults. High quality friendships are important for well-being and involve effectively resolving conflicts. Several famous quotes highlight friendship as a central part of life.