International Day of Families is observed on May 15, 2018. The holiday was established by the General Assembly of the United Nations in 1992. In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children.
From the perspective of children, the family is a "family of orientation": the family serves to locate children socially and plays a major role in their enculturation and socialization. From the point of view of the parent(s), the family is a "family of procreation," the goal of which is to produce and enculturate and socialize children.
However, producing children is not the only function of the family; in societies with a sexual division of labor, marriage, and the resulting relationship between two people, it is necessary for the formation of an economically productive household. (With material from: Wikipedia)