Query Expansion
A retrieval optimization technique that automatically rewrites or augments a user's original search query with synonyms or related contextual terms.
Think of It Like This
Like an experienced librarian hearing you ask for 'car fixing books' and automatically checking the catalog for 'auto repair manuals' as well.
Search queries are often short, ambiguous, or use mismatched vocabulary compared to the target documents. Query expansion uses language models or knowledge graphs to add relevant keywords, dramatically improving the recall of a search engine. It is heavily utilized in complex RAG pipelines to ensure the retriever finds the correct context.