What is Elasticsearch and what problems does it solve?

Elasticsearch is a distributed, open-source search and analytics engine built on top of Apache Lucene. It solves the problem of fast full-text search and real-time analytics over large volumes of data — tasks that traditional relational databases handle poorly. Common use cases include application search (e-commerce product search), log and event data analysis (the ELK stack), and business intelligence dashboards. Elasticsearch can index millions of documents and return search results in milliseconds, making it the industry standard for search-heavy applications.