The study of ideology hinges upon several important characteristics. First, the term “ideology” may connote different things to voters. To some, it indicates a preference for “conservatism” over “liberalism”; others adopt a more nuanced perspective, identifying ideology as “libertarianism,” “environmentalism,” and “populism” (among others). Some view it is an identity. Ideological labels are entrenched in political and non-political identities. The term “conservative” may signal a social orientation only loosely related to conservatism’s philosophical tenets (e.g., limiting the size and scope of the federal government). “Liberalism” or “progressivism,” signal a different worldview that also perhaps loosely related to the philosophical characteristics of modern (American) liberalism (e.g., “expanding the social safety net”). Ideology is also a means of cognitive organization; it is used to make sense of oftentimes complex public policy. Individuals organize policy beliefs around organizing principles, such as a preference for reducing the size of the federal government. Considering this heterogeneity, it is important to use the term with precision, in order to better understand how voters rely upon ideology in their decision calculus. Second, ideology is a central characteristic in the general structure of political beliefs. It acts as a lens through which the political and social world is interpreted. Third, ideology is functional in nature. Ideological preferences often fulfill a voter’s unique psychological, motivational, and personality-oriented characteristics. Finally, ideology has unique consequences in contemporary politics, as evidenced by increased political polarization, partisan-ideological sorting, and ideologically divisive rhetoric.