Every year right before the big game, CBS hosts a special where viewers get to vote on the greatest Super Bowl Commercials of the past 20 years. Originally cast via the cbs.com website, the special has allowed viewers to comment via social media to vote for their favorite commercial in more recent years. The special also features behind the scenes looks at commercials that are set to air during that year's upcoming Super Bowl. CBS shows the annual edition of "Super Bowl Greatest Commercials" on the Wednesday before Super Bowl Sunday.