AdWords Campaign Experiments allow you to test changes to your account on a portion of the auctions that your ads participate in. Like putting a bit of hot sauce on just part of your meal, Campaign Experiments give you a taste of the results so you can figure out whether you want to pour on the heat! This way, you can test changes to your keywords, bids, ad groups, and placements.
The results from experiments can help you make better decisions and help you increase your return on investment.