Lightning is Salesforce's new user experience and development platform that is designed to make users more productive and customize applications faster. It provides an intuitive interface that works across devices and uses reusable components to accelerate app development. Early adopters have seen significant benefits like 25% increased revenue, 24% higher win rates, and 50% faster customization times. Customers can move to Lightning by having their admin complete the Lightning readiness check and then encourage users to try the new experience.