What is the difference between avoid and prevent and ban and forbid ?Feel free to just provide example sentences.

avoid is to stay away from something on purpose.

prevent is to do something in order to stop something else from happening. getting a shot so that you don't get a disease would be preventing the disease.

ban is saying you can't do something. if drinking is banned, you can not drink. a person can also be banned. if you get into a fight at a restaurant, they can ban you.

to forbid is similar to ban, but it has more of a social feeling to it. if something is forbidden, you must not do it. doing something forbidden would get a bad reaction from people.