Hybrid search combines complementary retrieval signals. Keyword search is strong when exact terms, IDs or product names matter, while semantic search can find passages that express a similar idea using different words. A hybrid system blends or reranks the candidate results from both approaches.
A documentation search for a product might need to find an exact error code and also answer a question phrased as why login fails after a password reset. Keyword search handles the code; semantic search handles the question. Combining the two, then applying search reranking, is a common pattern for retrieval-augmented generation.
The best weighting depends on the content and query types. Evaluate with real searches, especially exact names and ambiguous questions, and measure whether relevant results appear near the top. Related: Semantic Search, Embeddings.