On HN You are a web developer. Let's assume you are building a website using Ruby(and probably Rails or any other Ruby framework). This is why you need to validate some input params - to make sure that they don't contain any crap you don't want to be there. Come on, you are going to google it, right?: Hmmm I need a regexp for emails. Googling: "regexp for email". Oh, nice one, I will use it. Oh, I
![Injects in Various Ruby Websites Through Regexp.](https://cdn-ak-scissors.b.st-hatena.com/image/square/44123574e3bbc4210f74559b9f067f1d1e90ba2c/height=288;version=1;width=512/http%3A%2F%2F1.bp.blogspot.com%2F-GiHwxKu6h98%2FT7dPthHm8TI%2FAAAAAAAAAJw%2F3wQ2TukKYQs%2Fw1200-h630-p-k-no-nu%2FScreen%2BShot%2B2012-05-19%2Bat%2B10.06.06%2BAM.png)