What is a soap?

What is a trailer?

Eastenders is a famous British soap

According to the web, a trailer is 'used to advertise an upcoming film, tv program, video game or product.'

What is a soap?
The soap opera genre originated in American radio serials of the 1930s, and owes the name to the sponsorship of some of these programmes by major soap powder companies. Tv soap operas are long running serials concerned with everyday life. The serial is not to be confused with the series in which the main characters and format remain the same from programme to programme but each episode is a self contained plot. In a serial at least one storyline is carried over from one episode to the next. A series is advertised as having a specific number of episodes but serials are potentially endless. Successful soaps may continue for many years: so new viewers have to be able to join in at any stage in the serial. In serials the passage of time also appears to reflect 'real time' for the viewers.