Apache Solr is an open source enterprise search platform built on Apache Lucene. It's designed to provide fast, reliable, and scalable search capabilities for any type of data, from text documents to structured databases. With its powerful features, Apache Solr makes it easy to set up and maintain a searchable repository of information. It allows developers to quickly develop and deploy search applications, and to customize the search engine's behavior. Apache Solr's scalability and flexibility lets developers tailor the search engine to their specific needs, making it an ideal solution for any size organization.