1. A Plugin is a computer program that interacts with a host application to provide a certain, usually very specific, function "on demand".
2. WYSI-Wordpress because its the only one its desactivated.
3. Yes
4. The do not usually work by themselves.
5. The main difference is that plugins generally rely on the host application’s user interface and have a well-defined boundary to their possible set of actions. Extensions generally have fewer restrictions on their actions, and may provide their own user interfaces.
6. They first began in the mid 1970s.
