Cancer is a disease that happens when the body makes cells that are not normal. These cells grow very quickly to take over the normal cells and can spread to different parts of the body if a doctor doesn't treat it. People can get very sick from cancer and even die. There are many different types of cancer, but you can't get any of them from being near someone who has it. But you can get some kinds of cancer from smoking, so that's another good reason to say no to cigarettes!