I have no idea why the UK riots happened

Let me start off by saying that beating people up and/or robbing them is bad. Burning down other people's property and businesses is also bad. Are we agreed on that? Excellent.

I spent the first 28 years of my life living in the UK and 4 of those years were in London. So it was depressing to see parts of that city going up in flames. However events such as this rarely trigger just one emotion and after the depression faded, it was replaced by curiosity. How and why did the riots happen the way they did? And what does this mean for preventing a repeat of them?

I'm not a newspaper columnist, so I don't claim to have all the answers at my fingertips. Instead I have a whole bunch of questions:

• Who were the rioters and the looters?
• What prompted them to start acting up?
• How did they communicate with and influence each other?
• Did the actions of the police hinder or help the situation?
• What role did on-lookers play?
• What led people to stop rioting and looting?

As tempting as it might be to blame one cause ("criminality", "cuts") that fits a particular view of the world, events like this tend to have overlapping causes (whys) and mechanisms (hows). If you have a ready-made answer then please keep it to yourself. If you have an interesting question then please add it via the comments.