Apache Solr is a highly scalable and fault-tolerant search platform based on Lucene. It provides distributed search and index replication. Solr indexes content into its internal representation format and provides a REST-like API to query the index. During indexing, documents are processed by analyzers which break text into tokens, then the tokens are stored in the index. During search, queries are processed by analyzers and the results are compared to the tokens in the index.