Thumbs Ups or Thumbs Down
Most sites that use or reply on user-generated content, provide mechanisms for “content consumers” to rate the content. The idea is that community members can vote or rate content, thus allowing the content with the highest rating to rise to the top.  From a UI perspective, there are a number of different ways to do this! Traditionally, many sites had made use of the popular 5-star rating system. These first appeared on video sites like Netflix and Blockbuster but very quickly became wide spread.

When Stars Don't Always Work
Stars are great when it comes to comparing two items of “known quality” – two movies for example. This approach works well for movies, videos, DVDs and the like. When it comes to searching for popular user generated content, however, figuring out what is or is not popular based on stars alone is limiting. In a 5 star system, it is difficult to find the “most popular” content because is unrealistic to sort content by stars alone (too many items have the same number of stars).  Incorporating the number of users rating the content into the equation doesn’t always work (which is more popular – a 2 star item rated 20 times, or a 5 star item rated 2 times?).

Voting vs. Rating
Say hello to thumbs up and/or thumbs down voting. Voting simplifies the process of measuring popularity (simply add up the number of votes).  True, voting can turn the rating process into a popularity contest but isn’t that what user generated content is all about? As long as safe guards are put in place to prevent abuse, voting usually represents the most simple (and perhaps the most accurate way) of measuring the popularity of content.

So the trick to using rating and voting widgets, is knowing when to use which! In situations where items lend themselves to objective comparison, or whose features are well defined and understood (movies, cars, consumer electronics, i.e.), rating may be the way to go. In situations where comparisons are more subjective or items are difficult to compare, voting systems tend to work best.