There are lots of ways to measure the success of an ad. But these days, the easiest and most visible method is just to look at the view count on YouTube. For this gallery, we've searched, scoured and sorted through the very depths of YouTube to find a reasonably definitive list of the most successful ads to date. We opted to omit movie trailers (which would eat up much of the list) and the numerous clips of "banned" international ad nonsense. The result is a pretty solid list that shows which ads people really feel are worth watching, again and again. Can you guess them all? You might be surprised. Click through to see the feature:
Video Gallery: The 20 Most-Watched Ads Ever on YouTube