You've probably heard security articles talk about JavaScript being used to attack websites, but you might not know why it's quite so dangerous. This video helps explain.

It's all to do with cross-site scripting: a vulnerability that allows hackers to inject client-side script into web pages that are viewed by other users. In the past, it's accounted for as much as 84 percent of all security vulnerabilities on the internet—so it pays to know at least a little about it. [YouTube]