This document discusses different definitions and understandings of ideology: 1) Ideology refers to a systematic set of ideas held by a group, like professional or class ideologies. 2) Some see ideology as distorting or concealing reality and producing "false consciousness." 3) Ideology shapes how cultural texts like films present the world. 4) For Barthes, ideology operates through unconscious meanings and naturalizing social constructs. 5) For Althusser, ideology is a material social practice reproduced through institutions like education, not just ideas. It constructs subjects and resolves contradictions in lived experience through illusions of free will.