We just discussed personalization in Sitecore, which is no doubt one of the most exciting capabilities Sitecore provides. However, having good, highly effective content is the first step to any personalized experience. What good is showing your customers content that should be interesting to your customer, if that content is arranged in a really crappy way or written poorly? Experience optimization, aka testing, tests different content variations and component layouts in order to determine which combination creates the most engagement value possible. Experience optimization, then, goes hand in hand with experience personalization. The two work together to create the most engaging, valuable experience possible for your customers and your business.