Why are women discriminated?

I know women are still discriminated even today but it was worse in olden times because they weren't aloud to go to college, vote or become politicians. I'm a man and I think that women can do anything men can do. In fact, the world would be nothing without women. I know because when I spent most of my school years in an all-boys' school (which is pretty much the same as living in a women-less world) I really hated it because I was always bullied there and I hated how there was never any girls there and I felt like I was living in hell.