If I go to a site, can the owner/moderator/someone on the website turn my integrated webcam on and monitor me?

My webcam is integrated into my laptop. I'm talking all websites including ones like the FBIs, Walmarts, schools, Best Buys etc.? Can they turn my webcam on if I visit their sites and visually watch me while I am on their sites? Can they turn my webcam on just from me visiting a website, like the people who run that website or the website itself. I'm worried about this guys, and also wouldn't it be illegal for a website to do this?