Feminism can be understood both as an ideology focusing on equal rights, opportunities and responsibilities for all people regardless of gender, and as a political and activist movement that strives to achieve this aim. Feminism is based on the understanding of reality that women as a group are treated as inferior to men as a group and that this is a structure that needs to change. Although many people who define themselves as feminists may agree with this description or parts thereof, it is important to point out that the exact meaning(s) of feminism and feminist practice can vary greatly depending on where, when and by whom the issue is discussed.

As there are a number of different feminist orientations, feminisms may be a more proper term than feminism. Examples of different types of feminism include lesbian feminism, liberal feminism, Marxist feminism, black feminism and transfeminism. The relatively large number of feminisms that have emerged gives an indication of a highly complex field where different people have different perceptions of what the problem in society really is and how it should be solved.

In the academic domain, there is feminist theory and a feminist theory of science. Central elements in both cases include analyses of power that question and challenge notions about truth, knowledge and what is natural (see also power, situated knowledge).