- What is a troll?

A Troll is a commenter on a thread who only seems interested in stirring up a reaction, rather than to contribute to a discussion.  In essence, a troll is picking a fight, seeking to annoy people they don’t even know just for entertainment value.  A troll is not visiting your blog for substantive engagement.

- What does a troll do in comment threads?

Trolls may say things they do not even believe, ignore substantive points or questions, issue a stream of pejorative insults, or simply drop links and run. 

- How to identify a troll

A quick test for trollery is to ask the suspected troll a substantive question related to the topic.  If the answer is only more of the same, that person may be a troll.

- Strategies for handling trolls

The best strategy, once a troll is identified, is to ignore them.  A common phrase is “Don’t feed the troll” though this is difficult if one holds out the hope of substantive engagement.  Eventually they’ll go away, which is as positive an outcome as you’re likely to get.

- What motivates a troll

It’s hard to say what would motivate someone to spend any of their limited time on Earth just annoying others whom they have never met.