Classism is not simply prejudice, but rather the combination of prejudice and institutional power. Anyone, regardless of class, can have classist prejudices, biases, or tendencies. However, in the United States, being upper class means having institutional power and privilege; therefore, classism here is the systemized discrimination of members of the lower classes due to the societal belief that having wealth is superior. Classism in America is systemic because it plays a role in our institutions and society, whether we recognize it or not. To truly understand classism is to also understand how it is embedded in institutional and cultural systems, rather than focusing on an individual's thinking or actions.
The poor may sometimes be a party to classism, without intending to act in that manner. and simply because classism is so ingrained in our institutions, cultures, and societies. For example, a member of the lower class may make an assumption that homeless people are lazy, or simply choosing to be homeless.
Anti-Classism refers to anything that actively attempts to challenge systems of classism. This could include strategies, actions, theories, and even language. A large part of anti-classism is first helping people to recognize that classism exists and present ways to lessen imbalances caused by systemic classism, in hopes of someday equalizing those imbalances.