Socialization is one of the most basic and general concepts in sociology, education and many other fields. It can refer to formal or informal behavior, rituals, processes or procedures used to introduce or orient young, new or novice participants to participation in a social organization. Socialization may include rites of passage, parenting, initiation rituals, probationary periods (like the period before tenure of faculty), or any form of education from apprenticeship to formal classroom courses and collegiate degree programs.
One meaning of the term is the process of communicating the culture of a society, community, group or organization to neophytes. This is especially important in the case of intergenerational transfer of fundamental behavior and attitudes from one generation to the next. Parents and families are especially important agents of socialization in this respect, whether in the case of personal conduct, ethics and values, religious beliefs, or political attitudes or beliefs about the value of education.
Schools at all levels are also important agents of socialization, whether in elementary school or medical or legal education. Thus, citizenship socialization of young children in the U.S. often focuses on the myths and meanings associated with holidays like the Fourth of July and Thanksgiving, learning the pledge of allegiance and the words to the national anthem. In the same vein religious socialization may involve learning the meanings of a variety of religious terms, prayers, the lyrics of religious songs, and proper ways of participating in religious services or observances E.g., for young children one of the most urgent lessons is when to be quiet and when to speak. Another is when and how to assume appropriate positions (e.g., standing, kneeling or bowing), or attitudes (e.g., culturally appropriate folkways associated with grieving). Socialization of young children often results in behavior that is considered "natural" by those in the particular culture, despite well-established knowledge in sociology and anthropology of enormous variations in the diverse cultures of the human community.
Adult socialization is a term used to describe socialization processes associated with a variety of status changes and admission to subcultures. The transition from adolescence to adulthood, getting married, becoming a parent, "coming out" (open acknowledgement of a gay, lesbian, transgender or other identity), grandparenthood, and retirement are some of the many adult transitions that frequently involve recognizable socialization activities.
Anticipatory socialization refers to "early" adoption of the attitudes, values or beliefs of a group or subculture to which an individual aspires. 
- Robert Merton. (source?)