This class act as a core component which reads/searches indexes created after the indexing process. It takes directory instance pointing to the location containing the indexes.

This class is the lowest unit of searching. It is similar to Field in indexing process.

Query is an abstract class and contains various utility methods and is the parent of all types of queries that Lucene uses during search process.

TermQuery is the most commonly-used query object and is the foundation of many complex queries that Lucene can make use of.

TopDocs points to the top N search results which matches the search criteria. It is a simple container of pointers to point to documents which are the output of a search result.