Feminism is the theory that people who identify as female should be treated in the same manner as their male counterparts. This has a variety of implications, including power-relationships, employment, beauty standards, use of language, and others. Let's explore what these few examples mean:
Power-Relationships: Historically in many cultures, women have been subjugated by men, meaning that they have been treated with less respect, received less power in decision-making and policy institution, and and generally been ignored or abused by men in order to maintain a hierarchy of power.
Employment: Across many centuries, there have been certain jobs that have been held primarily by men or by women. Oftentimes, these practices became seen as unwritten, or sometimes actually written, law, and people who tried to hold an occupation designated for the opposite gender were abused, ridiculed, and punished. Even today, when gender discrimination is illegal, many jobs continue to be associated with certain genders (doctors: men; secretaries: women).
Beauty Standards: Women have long been the object of art, and today many take issue with the fact that they are perceived as things to be looked at rather than as people. This practice is still a part of daily life, and women's bodies are used to sell practically everything - take a look at the ads around you. Because of their "object" nature, women's bodies are also expected to be taken care of, and beauty standards for men and women are very different. Men with gray hair or soft bodies can still be perceived as attractive, but it is rare for an older, out-of-shape woman to be popularly identified as beautiful.
Use of Language: This is one of the hardest parts of feminism for people to wrap their heads around because it seems ridiculous, but it's actually an indication of how deeply rooted gender is in culture. Language that has to do with men is generally positive: "Man up!", "Grow a pair!", and "You're the man!" all encourage people towards success in some way. On the other hand, language that gears more towards women is more often negative: "You run like a girl!" "Don't be such a b****!", and "He cried like a little girl" are all negative and inextricably linked with women.
What is an important element of feminism that confuses many people is that there are several types of feminists: those who seek equality, those who seek equitability, and those who seek dominance.
Equality: Women who want to have the same roles and respect as men. They hold the belief that all genders are equal and should be treated as such.
Equitability: Women who believe that women were subjugated for so long that they need to now be given special treatment to make up for centuries of abuse and disempowerment. They hold the belief that all genders are equal but that women have been put down for so long that they need a little bit of help before they can be treated and perceived as equals.
Dominance: Women who believe that women are superior to men and should become the more powerful gender, thereby shifting the balance in their own favor. This could be seen as a means to rectify past wrongdoings or as the natural order of things, depending on the person.