From this post by Steve Moore:
A mob, Young observes with considerable insight, is a group of fools and cowards. … Mobs rape, they lynch, they immolate, they beat, they terrorize, they loot, and they laugh. … And they are on the Internet.
…Mobs are senseless. They are the very definition of “insanity.” They exist in a world where all reality is—at least for a time—abandoned. They therefore tend to attract the senseless and the emotionally damaged.
They are bent on “justice” and will stop at literally nothing to get it. Every mob, however, defines “justice” for themselves. Hence, lynchings. Justice for mobs usually consists of vengeance or bile spewed on people they hate—frequently for irrational reasons.
If the justice system under which a group lives does not deliver the verdict, the penalty, or the speediness the group requires, a group of people who perceive that they have been wronged or disenfranchised can transform into a mob in an instant. It doesn’t matter to a mob what is truly right, what is legal, what is actually true, what is important or what is sacred.
…Trolls are vigilantes.
…Internet mob trolls guard their identity with their lives. Why? Because their lives would change forever if their secret hatreds were made public.
…Another Internet mob targets Amanda Knox for the same reason as did Leyland with Kate McCann—they believe her guilty, regardless of the evidence, and believe they, as Brenda Leyland said, are “entitled” to exact revenge.
…Amanda Knox haters frequently defend themselves by saying that they are fighting for the victim, Meredith Kercher, who was 19 when she was raped and her throat cut by a known burglar.
…People who send or re-transmit 25 – 100 angry, abusive social messages a day, (especially if to the same group of people) regardless of how right they believe their cause, must come to grips with the fact that they need help.
…Finally, if you are attacked by anonymous trolls, know this: They are afraid of you. If they weren’t, they would not hide their identity. Take comfort in the knowledge that they fear you, and they live in the shadows because they are terrified that one horrible day, they may be exposed and have to take responsibility for their words.
These are just snippets of an excellent article on Internet mobbing, by Steve Moore.