There are some things people do almost every day. Shopping is one of them. You can do the shopping in the supermarkets, department stores, shops and market places. Those people who buy things are customers. Those people who sell things are shop-assistants.
People who live in towns and cities can buy everything in a supermarket. It has many different departments or sections: the baker's, the dairy, the greengrocer's, the grocer's and others. They sell all kinds of food, clothes, toys, magazines and household goods in this big store. The things which are alike are in the same area. Even so, they are sometimes hard to find. Then the shop-assistant is always at hand and customers can address her/him for help. They can also ask questions at the Customers' Service Area.
Some supermarkets have deli and bakery departments where you can order what you want. In the other departments you take what you want from the shelf.