Foreigners are often surprised that there are no advertisements at all on the BBC television channels. The absence of commercials, as television advertisements are known, is 1 to the fact that the constitution of the BBC forbids it to accept advertising. So how does the BBC get the money it needs to 2 it going? In fact, the BBC is financed from revenue which is raised by the sale of television licences. The fee for the licences is set by the government, but 3 this, the BBC is not state-run, and it is proud of its independence. It 4 be said that the viewers themselves pay for the BBC, since everyone who owns a television has to purchase a licence. And of course, you have to have a valid licence whether you actually watch the BBC 5 not. This arrangement dates back to the 1920s when the BBC was a radio broadcaster. Some people feel the system is unfair 6 those who watch other channels but not the BBC, and there are those who fail to buy a licence, which is against the law. 7 an effort to combat this, the BBC has a fleet of detector vans that tour the country, checking if television is being used from an address when there is 8 record of a licence having been purchased.