From infancy humans are directed to other humans beings as the significant feature of their environment. Humans beings are social products, the human in us is primary created through our engagement with the social and cultural world , it is not individual and natural. Each individual learns ideals and behaviors expected from him as a member of society and develops a sense of self within a field of social relations and through the parameters of his culture. The way we are going to socially behave, how we will eat or dress, will not be individual but acquired depending on the society that we live on.
All societies in order to survive they depend on a number of social convention or implicit rules for behavior. This implicit rules will depend on the culture or values of our society, and will state what is permitted and what is not. If we are born in USA ,for example, there will be a norm which will stop us from eating other humans but if we are born in a cannibal society we will be taught that eating other humans is write. This norms change through out time as society change, some may vanish, some may be replace by others, some can be reinterpreted and others just remain. More over, norms can be extremely important, or not so important. For example "You shall not steal" is a key norm in many societies, whereas a rather less important norm in other societies is "You shall eat with your mouth close". There are some norms which can be valid for all humanity(Declaration of Human Rights), while other may concern only small groups, as the rules that impose a school to its students.
In general all norms are connected with sanctions in order to keep a social control, where individuals will follow rules as to evade sanctions. A positive sanction involves a reward for following the norm and a negative sanction involves a punishment for breaking the rules. Punishments for breaking sanctions can be more severe than others, for example if you kill somebody in USA you will receive death penalty, but if you paint a public wall with aerosols, your punishment will probably be to clean the wall, with rewards happens the same.
