More precisely, a role played by a person in some society involves usually the following:

• There is a public of other persons that know the role (to some extent),
• there are conditional actions, with conditions c_i and acts q_i such that a person who plays the role must do q_i if c_i,
• there are (usually) goals g_i such that a person who plays the role must (seem to) further g_i in any case, and
• there are rewards and punishments associated with the conditional actions and goals that are part of the role, that are usually meeted out by members of the audience.

Most human acting in society is acting in some role, acting out some part, that one has learned by learning its goals, rewards and punishments, associated values, conditional behaviour, and required appearances.

All of human social life is founded on the playing of roles, which is a kind of stage-playing mostly, in nearly all circumstances: Every human being, even the most simple one, is so complicated that he or she on any given moment can only act out and represent a small part of that the person may and can do. What one shows of what one is or would like to be is for the greatest part choice, and how one shows it is a combination of game and play, where 'game' refers to such sequences of playing that are bound by rules that one must have learned to play that game, and 'play' refers to spontaneous explorative activity, that is aimed at satisfaction of some end (like enjoying oneself or others), and when done with others involves cooperation and mutual consent.

Indeed, here lies a hidden and deep theme: The acting, stage-playing, role-playing that is the fundament of being human:"No man is as much himself as when playing a part." William Hazlitt.

This social stage-playing, that is part and parcel of every social role, is mostly necessary if only to prevent that the members of a group start fighting. Thus, it is necessary - because of: politeness, social graces, self-interest, social peace - to act as if, to play one's part, to keep up the pretenses, and to maintain a front and play a role one may not feel like while playing it, and that anyway only shows a fraction of what and how one is or may be. (See Johan Huizinga's "Homo Ludens"; Ervin Goffman: "The presentation of self in ordinary life"; and Eric Berne: "Games People Play", for respectively a historian's, sociologist's and psychiater's perspective on the subject of man the role-player.)

The subject is complicated, in part because the term 'role' has several senses that tend to apply to most roles as they are played, and because there is a lot of hypocrisy, delusion, pretense and falseness involved in the playing of roles by humans.

To clarify this some: A real king plays a real social role, which includes a lot of hypocrisy, acting as if, posing, posturing, lying and so on, all of which is necessary to make a minimally realistic and succesful king. A real actor who plays the part of a king on stage, plays a real role in a stage-play, that again involves a lot of hypocrisy, acting as if, posing, posturing and lying. The difference between the two kings - the real one and the one on stage - is that roles for a real king and for a real actor representing a real king differ, and require different skills.

Next, it is important to realize that in all human interaction play, pretense and reality overlap simultaneously on several, perhaps many, levels, apart from very extreme situations, and these are usually due to great pain, misery, or anger. All the rest of human social behaviour is made up of many layers of play and reality tht are mixed up and follow each others while roles are being played, partially but not completely according to the consciousness of the players that they are more or less serious, committed, pretending, or honest. (See: Awareness.)

One important problem is that the roles and role-playing of that vast majority of adult human beings is supposed by them to be precisely not the playing of games, but what they really are, and so the problems with the human playing of human roles in society are mostly

(1) the dishonesties in much role-playing: People pretend systematically that they are other than they think and feel, and do so from fear and self-interest, because they believe that the role they play cannot be played without their kind of lying.
(2) the belief in their own parts and pretenses: The vast majority of adults beliefs that what they are to a large extent coincides with their social position and role.
(3) the inability to stop playing the role one plays: The vast majority of adults is not capable anymore to act spontaneously (without drink or drugs), and adulthood has come for them with an identification with some roles one plays, the personality they pretend to themselves and others they are. One "is" a clerk, manager, police-man, housewife and so on, and feels "in duty bound" thereby to feel, think and act as (one believes that) a a clerk, manager, police-man, housewife and so on feel, think and act - for after all, that is what one "is" (one feels, and has been told). 

Here lies also the fundamental difference between children and adults: Children also play roles all the time - except that they still know that they play, and have not yet identified themselves with a social role (other than: a playing child).

Children can unproblematically and directly give up a role they play and return to themselves; almost all adults are hardly capable of giving up the social roles with which they identify themselves - and which tend to be living lies composed from self-deception, even though this also is normally mostly hidden to the adults.

Adults who drop out of their roles tend to do so socially and in groups, for example in soccer-stadions, where tens of thousands of average males anonymously try to  scream out of their systems a week of frustration and self-falsification, or else happens with drinks or drugs on parties, where deviant behaviour and acting out once more belong to the acceptable social game one plays there. 

A warning may be in place for the naive reader:

There are people who enjoy pretending that they are "authentically" "themselves". One may find such persons in the context of religious or therapeutical groups. Normally, this too is a pose, a pretense, and a role - and it also tends to be a neurotic one, that is mostly used to feel superior to others or to enable one to do as one pleases while falsely pretending one is entitled to do so because one is so "authentically oneself". The truth is that whoever cannot act normally to and with normal people most probably is disturbed. Also, the playing of roles, the keeping up pretenses, and the common courtesies and niceties that belong to playing a social part, and which one does not do because one feels like doing it but to help each other, are part and parcel of being a social human animal.