Friendship is a relationship of mutual affection between people. It is a stronger form of interpersonal bond than an "acquaintance" or an "association," such as a classmate, neighbor, coworker, or colleague. Although there are many forms of friendship, certain features are common to many such bonds, such as choosing to be with one another, enjoying time spent together, and being able to engage in a positive and supportive role to one another. Friendship has been studied in academic fields, such as communication, sociology, social psychology, anthropology, and philosophy. According to Northern Illinois University psychologist and friendship expert Dr. Suzanne Degges-White, "True friendships are hallmarked by each members desire to engage with the other – its about mutual interest in one anothers experiences and thoughts, as well as a sense of belongingness and connection". Friendship in adulthood provides companionship, affection, and emotional support, and contributes positively to mental well-being and improved physical health.