Why do people talk too much?

I know a number of people who talk too much. They do not realize that it is very counter-productive. When you are talking you are not listening and cannot learn. You also encourage the other person to drift off and think of something else. They also do not have the chance to ask questions and often instead of persuading them to your opinion, it actually dissuades them. Many of us have the tendency to talk to much, but it is a good habit to deliberately pause and allow the other person to talk or ask questions. In fact it is a good idea to encourage the other person to talk.