Good and bad manners make up the social rules of a country. They are not always easy to learn because they are often not written down in books. For example, British women didn't go into pubs at the beginning of this century because it was not considered respectable behaviour for a woman.
Now both women and men drink freely is pubs and women are fully integrated into public life. Visitors to Britain are often surprised by the strange behaviour of the inhabitants. One of the worst mistakes is to get on a bus without waiting your turn in the queue. The other people in the queue will probably complain loudly! Queuing is a national habit and it is considered polite or good manners to wait for your turn.
In some countries it is considered bad manners to eat in the street, whereas in Britain it is common to see people having a snack whilst walking down the road, especially at lunchtime. Britons may be surprised to see young children in restaurants in the evening because children are not usually taken out to restaurants late at night. And if they make a noise in public or in a restaurant it is considered very rude. In recent years children are playing a more active role and they are now accepted in many pubs and restaurants.
In recent years smoking has received a lot of bad publicity, and fewer British people now smoke. Many companies have banned smoking from their offices and canteens. Smoking is now banned on the London Underground, in cinemas and theaters and most buses. It's becoming less and less acceptable to smoke in a public place. It is considered rude or bad manners to smoke in someone's house without permission.
Social rules are an important part of our culture as they passed down through history. The British have an expression for following these "unwritten rules": "When in Rome, do as the Romans do".