Wow - sounds like you're reading some interesting stuff! A "sit-in" is also known as an "occupation". Protesters occupy a place of importance like a government buillding or a workplace. It doesn't imply necessarily that they do it illegally or with violence, though it is possible. The main point is that it is an intended to be inconvenience to the authorities who will want to move them on. A "protest camp" is normally situated near a place which the protesters regard as linked to an immoral activity e.g. in England and Scotland, we have protest camps near nuclear weapons installations. The camp is at least semi-permanent to provide a longer-lasting symbol of and base for protest. again, the protest is not necessarily violent. Hope that helps, Michael