Well Questioner, you could look it up on Wiki and see it's the part of Christianity that believes in being "born again" and bringing the Word of God to everyone who hasn't heard it.
I also think that they are the most annoying part of Christianity. And, while some have said that the Golden Rule is "do unto others as you would have them do unto you", that means that sharing the Word of God is the best thing that someone could do to them, meaning they should do it to everyone else.
Sorry, but I don't believe like that. Matter of fact, I believe the opposite, "DON'T do unto others as you wouldn't like to be treated". I don't like it when people try to push their views off on me, so I don't do it to others. However, if a person starts a conversation with me about spiritual things, I'm willing to talk to them and will respect their views, as long as they respect mine. If they start pushing their brand of spirituality off on me as the only "right" one, that is where I part ways with them.
Personally? I think that God is too big to be contained in just one dogma or religion. I believe that all religions have pretty much the same thing (something better, something worse, what we do in this life determines what happens next, there is a force for Good, and there is also a force for Evil, etc.), and because of that, I view God as a multiple faceted being, with each facet being represented by a major religion.