# Vector Database

> A database built to store embeddings and retrieve the nearest ones to a query vector using approximate nearest-neighbor search.

_The Agentic Web Lexicon · /glossary/vector-database · [JSON](/api/glossary/vector-database) · [all The Agentic Web Lexicon](/glossary)_

- **term:** Vector Database
- **category:** knowledge-memory
- **short_def:** A database built to store embeddings and retrieve the nearest ones to a query vector using approximate nearest-neighbor search.
- **long_def:** A vector database (or vector store) indexes high-dimensional embeddings and finds the most similar ones with Approximate Nearest Neighbor (ANN) algorithms — commonly HNSW graphs or quantization — under metrics like cosine distance. It is the storage-and-retrieval backbone of RAG: documents go in as vectors, a query vector comes in, and the closest chunks come out as context.
- **see_also:** embeddings, rag, agentic-rag
- **etymology_origin:** A database category that emerged with the rise of embedding-based retrieval; popularized by systems such as FAISS, Pinecone, Weaviate, Milvus and pgvector, using ANN indexes like HNSW.
- **related_to:** embeddings, rag, agentic-rag, grounding
- **contrast_with:** Unlike a relational database, which retrieves rows by exact field matches, a vector database retrieves items by approximate nearest-neighbor distance between embeddings — similarity ranking rather than exact lookup.
- **example:** Vector databases such as Pinecone and Weaviate use HNSW-based Approximate Nearest Neighbor search over embeddings to return the most semantically similar documents to a query.
- **source:** https://en.wikipedia.org/wiki/Vector_database
- **status:** active
- **why_it_matters:** The vector database is where your content lives once an AI system ingests it; content that chunks and embeds cleanly is retrieved more accurately into the answers agents generate.
- **sameAs:** https://en.wikipedia.org/wiki/Vector_database
- **bridge_entity:** models
- **last_verified:** 2026-06-15
- **md_twin:** /glossary/vector-database.md