All media texts are full of representations of the exterior (you could call it 'the real') world and as whole things are themselves representations. Media texts will represent types and groups of people, places, times, opinions, ideas, concepts, events and actions to us and we have to try and work out where the representations come from and what they are doing. All such representations are mediated and are not the things themselves but media constructions made out of the idea (that is someone's or some group's idea) of the thing.
One of the first issues to get to grips with is that of typing and stereotyping by the media. Typing is the ascription of assumed group characteristics to an individual that is assumed to be a member of the group in question. It is a very common human behaviour and we all of us do it all the time to make sense of people and groups we know little of. Stereotyping is the same activity, lumping someone into a group without knowing if they really are a member of that group, carried out with negative intent or effect. So to make assumptions about a person or group you do not know is typing but to make those assumptions with the intent or effect of denigrating, dismissing, disempowering or harming someone is stereotyping.
Stereotypes can be very hard to erase or change once someone has adopted a particular attitude. The point is that a stereotype is a habit of mind (an idea which is habitually used without critical awareness by a person) and so is a part of the person who uses the stereotype. It is common for strongly established stereotypes to become deeply rooted in the common sense of a culture and these widely held and un-critically accepted habits of mind are the most dangerous stereotypes. They are the ones most likely to be acted on and they are the ones most likely to lead to a moral panic (consider these instances – http://en.wikipedia.org/wiki/2005_Birmingham_riots http://en.wikipedia.org/wiki/Emmett_Till).