Frequently, we hear the following terms used interchangeably: breaker and fuse. They are similar in that are both electrical overload protection devices, but they work differently.
This photo is from a house in which 4 outlets caught fire and had 2 blown switches (click the image to full-size). This was not an old house. Some people think that because of the age of their home, they should be fine and everything should be in great working order. In most cases you would be right, but that is not always the case.