Ideologies are the 'generally accepted' ideas about life, society and the world that most people in society share with others.
Ideology is an aspect of discourse analysis.
Ideologies are what create a society or culture's mindset or world view; they suggest to us that whilst life isn't perfect, we live in or are working towards 'the best possible of all worlds'. i.e) Our society's beliefs are the right ones and the other's beliefs are less enlightened.
We are conditioned into accepting these ways of thinking as we grow up, as the family, religion and school instil and reinforce and maintain such values.
Importantly, these ideologies come to us through the language we meet and use in our everyday lives.
For example, ideological language is used in the tabloid newspaper headline; 'Yob culture leads to dumbing down of BBC drama output'

Read more about Ideology
Read more about binary opposition here and here
Read more about narrative