Algolia is a SaaS search engine. You send your data (product catalog, job postings, articles) to Algolia, configure ranking and facets, and get a fast search API in return. Features: typo tolerance (find "sears" when searching "sears"), faceted navigation (filter by brand/price), geo-search, analytics, and sub-100ms latency. Used in e-commerce, job boards, content discovery, and any app where users need to find things. Typical workflow: index data → configure ranking → embed search UI → analyze user behavior → iterate.