Score Boosting 
Lucene allows influencing search results by "boosting" in more than one level:
- Document level boosting - while indexing - by calling document.setBoost() before a document is added to the index.
- Document's Field level boosting - while indexing - by calling field.setBoost() before adding a field to the document (and before adding the document to the index).
- Query level boosting * - during search, by setting a boost on a query clause, calling Query.setBoost().