Definition
Semantic search is a search technique that uses embeddings and vector similarity to find documents that match the meaning of a query, rather than requiring exact keyword matches. It can find a document about "account recovery" when you search "reset password" because the concepts are semantically related. Semantic search is the retrieval mechanism that powers RAG systems and AI knowledge bases.
Example
A support bot uses semantic search to find the right help article even when the customer describes the problem differently than the article title: "I can't get in" matches "Login troubleshooting guide."
Why it matters
Semantic search makes it easier to find useful information when people phrase a query differently from the source material. It is commonly used in RAG systems and AI knowledge bases.
How it differs from RAG
Semantic search retrieves relevant content. RAG uses retrieval, often semantic search, and then generates an answer grounded in the retrieved content.