Hybrid search combines results or signals from more than one search method. A common design pairs lexical search, which matches words and identifiers, with semantic retrieval, which finds meaningfully related material.
The combined system needs a method for reconciling results, such as combining ranks or normalized scores. Its usefulness depends on the data and queries, so evaluation should test whether the combination improves relevant results rather than assume that more methods always help.
ELI5
Hybrid search uses more than one way to find information. One method can look for exact words while another looks for similar meaning.
For example, a support search could use exact matching for an error code and meaning-based search for the user's description of the problem. Combining both can find a page that either method alone might miss.
Why combine keyword and semantic search?
They handle different kinds of queries well: exact identifiers favor word matching, while paraphrases often benefit from meaning-based retrieval.
Does hybrid search always outperform one method?
No. The combination and its settings must be evaluated on representative queries and relevance judgments.
