Search indexing is crucial for enhancing user experience on websites. It involves mapping search queries to web pages or documents and can be created through web crawlers or APIs. Full-text search entails indexing each word on a site, while AI-powered search engines understand context to provide richer results. There are two primary ways to build a search engine index: using a search crawler or directly pulling data from a database via APIs. Optimizing a search index can be done in various ways such as adding open graph tags, schema markup, and enhancing the index with off-site data like product ratings and inventory levels. Personalization of search results is also important to cater to individual customer preferences.