A dress code is a rule about what people should wear. Many times these rules are obvious: they do not need to be written. For example, when walking around a city or going to work one needs to have appropriate clothes. These can change depending on different countries and cultures. At other times a dress code can be a written rule: this can happen for important events. Some private places might also have a dress code that people need to follow to be allowed in - for example churches and nightclubs.