initially, from what I understand, its about keeping out western influences.

when it becomes impossible, or, as in the case of some countries, their governments (unelected) are seen to be in league with the west ... or in some cases are seen as puppets of the west ....then it turns to hatred of the west.

especially where people who oppose the west/the government are tortured - as happened under the Shah, (and yes it also happened under the Ayatollah), and as also happened to people like Sayd Kutb, who later influenced bin Laden's right hand man, Zawahiri.

Most of the time it is clashes between local groups, especially victimisation of 'westernised' individuals. These are the people who are most likely to be victims in many middle eastern countries, and they are also the ones who will be beaten by cultural fundamentalists in India.

The next most vulnerable group are political figures - and there have been a few assassinations over time that have been related to these issues.

When it begins to overflow into attacks on western interests this is usually because they are available (eg occupying troops, KFC outlets).

The fourth level is attacking 'at source' - eg 9/11. This was most likely a one off, but was calculated to, and DID inspire attacks by homegrown groups, enabling the conflict to spread to the west. A sense of alienation from mainstream society combined with religious/cultural identity and a 'victim' interpretation of their situation (its more complex than that, but to keep it brief these are the main points) makes certain people vulnerable to extremist interpretations, and more likely to make 'sacrifices' in the name of belief.

We are still a lot safer than people living in the regions where these conflicts originate, and for the most part the hatred of the west isn't the driving force behind people's day to day actions. Its mainly a protectiveness of what they identify as their own culture, values etc.