As a developed society, we follow certain code of conduct and we expect others to follow that as well. But, it isn't always easy to make people follow the same rules. When the things go out of control, we either protest or we simply ignore.
Some people decide to not ignore and they are ready to fight the system.
This is when Social Revolution takes birth. The spark can come in the most subtle way but it can go a long way if its gets support and people like the idea.
Over generations, human race has evolved and we have witnessed massive changes.