There are five main types of censorship discussed - moral, military, political, religious, and corporate. Moral censorship removes obscene materials, military censors to keep secrets, political censorship hides information from citizens, religious censorship removes inappropriate content, and corporate censorship stops negative publicity. While censorship can be necessary, it should not limit basic rights and cannot be justified for personal profit. An example given is Viacom suing YouTube and regulating expression through copyright lawsuits and censoring critical videos.