This chapter explains the importance of learning from failed experiments to succeed in achieving goals. Experiments that fail tend to contradict some assumption held by the tester, and the results can point to reasons why that assumption is wrong. A/B testing is very prominent among e-commerce businesses. It is highlighted in this chapter that many retailers have customer reviews and star ratings displayed on their sites. It is found that a large online retailer discovered through testing that displaying the rating prominently on individual product pages helped conversion. It is concluded that any test that reveals that an initiative is not performing is a blessing in disguise as it allows the tester to free up resources from things that are not working and divert them to the things that are.