The socialization process begins in infancy and takes off once a child begins to understand language. Socialization happens without our realization through our observations and interactions with others, and continues throughout our lifetime.
We each have personal, and unique identity that separates us from other people, and in sociology it is called the self. The idea that our self comes from the value we put into the opinions other people have of us is called the looking-glass self.
Here a boy plays the role of a mechanic, a typical male dominated career. Roles are behaviors or functions expected of us to play from a particular status.
Here two girls are taking on the role of leaders by reading the map while the rest of the group hangs out in the background, this is an example of what George Mead calls the generalized other. In simplest terms it is when we imagine what the group expects of us and act upon that role. In this case these girls are taking on the roles of leaders because that is what they think the group expects of them.
There is an unspoken agreement between all passengers on a metro to keep to yourself. This particular type of norm is called a feeling rule, it regulates acceptable displays of emotions in any given situation.