Because so many people came to attend the plays, the Greeks built massive outdoor theatres on hillsides so that people could be placed so that they could see what was going on down in the orchestra pit—the stage area. The entire seating section was dubbed the Theatron, which is where the word "theatre" comes from. These days, because there are so many TV sets, some people think that all the action must be taking place behind the screen but that's not true. The actors are doing their acting right up on the stage before your very eyes. The Greeks had very few locks on doors back then, which is why we enjoy watching their theatre performances today. If someone wants to make sure that no one enters or leaves the theatre during a performance, they will close off access with a rope tied around the neck of a large dog. The dog's leash will go through the door handle so that when its nose gets near the lock, it will let out a warning sound and move away from the door. This means that customers within hearing distance will know not to go inside unless they want to get barked at by the dog. You may wonder how the actors would know if someone was sneaking in during a scene that has not yet been played. Well, there are two ways about this. First, they might hear someone come in through one of the side entrances and then leave again after being silent on the other side of the door.