Elasticsearch is a distributed, RESTful search and analytics engine designed for horizontal scalability and near real-time search capabilities. It allows you to store, search, and analyze large volumes of data quickly. Built on top of Apache Lucene, Elasticsearch is commonly used for log and event data analysis, full-text search, and handling complex queries in a wide variety of use cases, including web search engines, enterprise search, and data analytics platforms. Its powerful features include support for structured and unstructured data, high availability, and full-text search with sophisticated filtering and ranking capabilities.