Write a summary of the following passage (Max5-6sentences).

Advertising has become a very specialized activity in modern times. In the Business world of today, supply is usually greater than demand. There is great competition between different manufacturers of the same kind of product persuade customers to buy their own particular brand. They always have to remind the customer of the name and the qualities of their products. They do this by advertising. The manufacturer advertises in the newspapers and on posters. He sometimes pays for songs about his product in commercial radio programmers. He employs attractive sales-girls to distribute samples of it. He organizes competitions with prizes for the winners.  He often advertises o the screens of local cinemas. Most important of all, in countries that have television he has advertisements put into programmers that will accept them. Manufacturers often spend large sums of money on advertisement. We buy a particular product because we thing that is the best. We usually think so because of the advertisement that say so . Some people never pause to ask themselves if the advertisement are telling the truth