Thumbs system on Urban Dictionary

I was thinking of implementing a thumbs system, but mine would require a registration thus ruling out the possibility of people voting more than once unless they create a new account to do so. So I was wondering about Urban Dictionary's thumb system. How does it work? I would imagine that my IP would be stored in a database, so people would not be able to vote more than once however IPs do change pretty often and especially when you're on an iPhone. Probably a combination of cookies and IP checking. Can anyone give me a better insight? What would they check for to ensure you don't vote more than once?

The reason I ask is because I may want to make my a public system instead. Maybe even a hybrid, similar to SO where you can ask a question before creating an account and then have the two linked toget开发者_Python百科her. I am using PHP and MySQL.

Almost always it's done with cookies. As you say, IPs can't be used (naively) as they change, or cover too many people (i.e. everyone in a given office, etc).

But online polls not reliable anyway, so don't get too concerned about solving a problem no-one cares about. You can implement more 'intelligent' rules but then you need to ask what benefit you are getting for all your work.

Personally, I would go with:

1. Cookies
2. Forced signup voting
3. Some sort of analysis of voting patterns

Because it goes without saying that people can just sign up constantly, to submit more votes. It really depends on what benefit people get from voting, and how much you care (in terms of time, which is, obviously, money).

I know urban dictionary allows for more than one vote per day. Once every six hours to be exact.