The term human bond, or more generally human bonding, refers to the process or formation of a close personal relationship, as between a mother and child, especially through frequent or constant association. When pairs have favorable bonds, the nature of this bonding is usually attributed to "good" interpersonal chemistry. The word bond derives from the 12th century Middle English word band, meaning something that binds, ties, or restrains. Its application to interpersonal human relationships has been used intermittently ever since.