Riot grrrl is a group of people who want girls to be able to do all the same stuff as boys. They think it's not fair that boys get to do things like play in punk rock bands and skateboard while girls have to be quiet and behave.
So, they decided to make their own clubs and groups where girls could be loud and angry too. They call this group Riot Grrrl. They have meetings, make their own music, and even put out their own magazines. They basically just want girls to be able to be themselves and not have to fit into some boring stereotype of what girls are supposed to be like.
These Riot Grrrl people also talk about how important it is for girls to stand up for themselves and each other. They believe that girls can do anything that boys can do and that they should be able to do it without anyone saying they can't. They also talk about how important it is for girls to support other girls because it helps everyone be stronger.
So in short, Riot Grrrl is a cool group of people who want girls to be able to do anything and be themselves without anyone telling them they can't.