Ideology is a collection of beliefs, values, a system of ideas and ideals which forms the basis of a theory or policy. Sometimes, ideology refers to a group of political beliefs or a set of ideas that characterize a popular culture or group of people. Capitalism, Communism, Socialism, and Marxism are some common example of ideologies.  Ideology always emerges among the supressed class of the society. French Marxist philosopher Louis Althusser, defines that ideology is

“The imagined existence (or idea) of things as it relates to the real conditions of existence”

Ideology emerges with some common comments and thing among the group of people, here are few of them:

Common Language

Common language plays an important role in evolving. People have same language could be agreed upon and ideology, if they they found that their language is in danger or being ignored.

Common Identity

Common identity like: nationality, cast, region etc can also cause an ideology to emerge to support their unique identity.

Common Religion

Religion perhaps the most important thing in the emergence of an ideology. Common religion among people is source of uniting people and keeping people think together.

Common Ideology

Existence of common ideology among a group of people may also be the source of emergence  of a new ideology having roots from the previous ideology.

Sources of Ideology

There are always some sources of ideology to evolve.

Leadership

Without the leader, there is no movement. Often leaders defines the way for a nation to lead and grow and more often leaders gave ideologies to their nations.

Hatered

When a group of people is hatered having common things like mentioned above can rise an ideology to protect their common thing.

Imitation

The less satisfaction form ourselves can cause an ideology to be like other. The more we mistrust and judge ourselves the more likely we may follow others.

Coercion

People forcibly converted to other religion, identity or languages causes and new ideology to evolve.