Are you human? (or How to prevent spam)
- by pek
What mechanisms do you know that prevent your site from being abused by anonymous spammers.
For example, let's say that I have a site where people can vote something. But I don't want someone to spam something all the way to the top. So I found (a) creating an account and only allowed to vote once and (b) CAPTCHA to decrease spam. What other methods do you know and how good do they work?