This chapter examines the evolution of feminism as an ideology using the analogy of ‘waves’, a term that indicates high points of debate and activism followed by more fallow periods. It first traces the historical origins of feminism from the first to the third wave and a possible fourth. It then considers whether feminism is an ideology in its own right and goes on to identify variants of feminism such as liberal feminism, separatism and political lesbianism/lesbian feminism, transfeminism, revolutionary feminism, eco-feminism, and black feminism. The chapter also explores the links between feminism and other ideological perspectives as well as the connection between the national and global dimensions of feminism and the ways in which feminist ideology has been expressed in political movements and shaped the policies of governments and international organizations. Finally, it tackles the question of whether ‘post-feminism’ has rendered feminism obsolete.