Apache Solr is an open-source search platform built on top of the Apache Lucene library. It is designed to provide powerful full-text search capabilities, enabling users to quickly find relevant information in large datasets. Solr supports various features like faceted search, filtering, and real-time indexing, making it suitable for applications that require efficient data retrieval. Solr is widely used in various industries, including e-commerce, publishing, and enterprise search. It can handle complex queries and offers scalability, allowing it to manage large volumes of data across distributed systems. Its REST-like API makes it easy to integrate with different programming languages and applications.