I do not understand 'trolling" please explain?

On this site, I answered a question with a question, short, nothing mean-spirited, I forgot the format, the rules: "Do not answer a question with a question." My question today is, do people really troll in order to get questions and/or answers deleted, just because it makes them happy, or is this done by the managers of the site? Hey, I'm no angel, I have reported, but I reported two blatant racial slurs. What kind of site is this?