Feminism seeks to advocate for social equality between men and women and oppose patriarchy and sexism. There have been three waves of feminism focused on different issues - the first wave in the 19th/early 20th century focused on women's suffrage, the second wave in the 1960-70s addressed discrimination and cultural/social issues, and the third wave beginning in the 1980s addresses intersectionality across class and race. Central feminist themes examine the social construction of gender versus sex, the public/private divide, and patriarchy as a system that oppresses and exploits women. Broad streams of feminist thought include liberal feminism seeking absolute equality, radical feminism arguing women's subordination cannot be addressed within other systems,