What is Ideology

What is ideology and what are the 2 basic ideologies that shape American political behavior?  In other words, help define ideology and explain the basic political assumptions of the 2 dominant ideologies in America.  What political groups and demographics (Give 2-3 of each) are attracted to each ideology given their principles?  Finally, which ideology (or principles if you want to take from both sides) do you most agree with and why?  What are the weaknesses of the opposing view and what are the strengths of your ideology.  Use evidence and examples from history and practice to defend your principles.