Search relevance is crucial to user experience, but achieving the right level of relevance can be challenging and requires constant monitoring and adjustments. A/B testing is a valuable tool for measuring the impact of changes in search algorithms and configurations on key performance indicators (KPIs). By running A/B tests, businesses can validate their decisions in real-time and make confident changes to their search experience. Some important examples of types of tests that can be run to improve KPIs include leveraging social proof, experimenting with indexed content, testing search merchandising techniques, personalizing search results, and optimizing the balance between too many or too few criteria for search rankings. A/B testing is essential for websites with a catalog of content that users frequently browse and explore to ensure relevant results and maintain user engagement.