To ban means to officially forbid something or prevent someone from doing something or going somewhere. When a school bans cell phones during class, students aren't allowed to use them. When a library bans a person for breaking rules repeatedly, that person can no longer enter the building. A country might ban certain products from being sold, or a sports league might ban a player caught cheating.

A ban can also be used as a noun: “The principal announced a ban on trading cards after they caused too many playground arguments.”

Bans come from people in authority making rules. Your friend might refuse to play a certain game with you, but only a referee or tournament organizer can actually ban it from competition. Similarly, your parents might not let you watch certain shows at home, but when a government bans a book, it can become illegal for anyone in that country to sell or own it.

The word suggests something serious and official. Breaking a ban usually leads to real consequences: punishment, fines, or removal from a place or activity.