No one is born knowing how to greet a stranger, what to wear to a funeral or which foods are fit to eat. Babies arrive with remarkable capacities for learning, but the content of what they learn comes from the people around them. Sociologists use two linked ideas to describe this: culture, the shared way of life a group passes on, and socialization, the process by which each new person comes to share it.

What culture includes

Culture includes material objects, such as tools, clothing and buildings, and nonmaterial elements: symbols, language, values and norms. Symbols are anything that carries a shared meaning, from a flag to a thumbs up. Values are broad ideas about what is good and desirable, such as freedom, family or hard work. Norms are the rules and expectations that guide behavior in particular situations.

Not all norms carry the same weight. The American sociologist William Graham Sumner, in Folkways (1906), drew a famous line. Folkways are everyday customs, such as saying thank you or not wearing pajamas to a job interview. Mores are norms with moral force, such as prohibitions on theft or cruelty to children. In short, mores carry strong moral weight, while folkways are everyday customs. Break a folkway and people think you odd; break a more and they think you wicked. The strongest mores, taboos, are so deeply held that the very idea of breaking them provokes disgust.

Looking at other cultures

Sumner also named a tendency found everywhere: ethnocentrism, judging another culture by the standards of one's own. To someone raised on forks, eating with the hands may seem unclean; to someone raised eating with the hands, sharing a fork that has been in other people's mouths may seem worse. Some ethnocentrism is natural, but unexamined it blocks understanding.

The scholarly response is cultural relativism: trying to understand a practice within its own cultural context before judging it. As a method, relativism is powerful. It forces researchers to ask what a custom means to those who follow it. But using cultural relativism as a method does not require approving of every practice one studies. A sociologist can explain why a society practices forced marriage and still hold that it violates human dignity. Understanding comes first; it does not have to be the last word.

Becoming a self

Socialization is the lifelong process through which people learn the culture of their society and develop a sense of self. Rare cases of children raised in extreme isolation show how much depends on it: such children often struggle with language and social life long after rescue.

The American sociologist Charles Horton Cooley offered a vivid image of how the self forms. In Human Nature and the Social Order (1902) he quoted a couplet: "Each to each a looking-glass / Reflects the other that doth pass." His looking-glass self is the idea that we form our self-image from how we imagine others see us. We imagine how we appear to others, imagine their judgment, and feel pride or shame in response. A child repeatedly told she is clever, or careless, often comes to believe it.

George Herbert Mead, a philosopher at the University of Chicago, described how children learn to take the perspective of others. In play, a small child takes the role of one specific person at a time, pretending to be a parent or a teacher. In organized games, a child must keep in mind the roles of everyone on the field. Eventually people internalize the generalized other: the general expectations of the community as a whole, a sense of how "people" expect one to behave.

Agents of socialization

Families are the first agents of socialization, passing on language, religion and assumptions about the world. Schools teach reading and arithmetic, but they also teach a hidden curriculum: lessons in obedience, punctuality and competition taught through school routines rather than through any official subject. Peer groups matter more as children grow, and media of all kinds supply models of how to live. Socialization never fully ends. Starting a job, becoming a parent or retiring all bring new learning. Sometimes the process is deliberate and intense. The Canadian American sociologist Erving Goffman described total institutions: places where all of life happens under one authority, cut off from wider society, such as prisons, military boot camps and some psychiatric hospitals. In them, people often undergo resocialization, in which old identities are stripped away and new ones built.

Worked example: basic training

Jordan, eighteen, arrives at military basic training. Within hours Jordan's hair is cut, personal clothing is replaced with a uniform, and every hour of the day is scheduled. This is a total institution at work: resocialization begins by removing marks of the old self. Over the following weeks drill instructors reward and punish in public, so the looking-glass becomes the platoon's gaze. Jordan learns new folkways (how to address an officer) and new mores (never abandon a fellow soldier). By graduation Jordan has internalized a new generalized other: the expectations of the unit. The same process shows why such institutions need careful oversight. Power that can reshape a person can also be abused.