Knowledge Graph
A knowledge graph is a structured representation of entities (people, products, customers, drugs) and the relationships between them, stored as a graph and used to ground AI systems in verified, queryable facts rather than free-form text.
AIDOLS Research Team · Editorial standards
Full definition
Knowledge graphs encode the world as nodes (entities) and edges (relationships), often with rich attributes and provenance. Google's Knowledge Graph powers Search facts panels; enterprise knowledge graphs in pharma, banking, and supply chain encode regulated relationships. The 2024–2025 "GraphRAG" movement combines vector retrieval with knowledge-graph traversal to produce richer, more accurate LLM grounding than vector-only RAG.
Why it matters
Knowledge graphs are the structured counterpart to vector embeddings. Where vectors capture similarity, graphs capture relationships and provenance — what cures what, who reports to whom, which suppliers serve which products. For high-stakes enterprise AI, hybrid graph + vector retrieval often delivers materially better factuality than vector-only RAG.
Example
A pharma company combines a 50M-edge knowledge graph (drug-target-disease-trial relationships) with vector RAG over its internal research library. The combined system answers complex queries like "which Phase 3 trials targeting the same pathway as drug X failed for safety reasons?" — impossible with either system alone.
Next steps
Related terms
- Retrieval-Augmented Generation (RAG)Retrieval-Augmented Generation (RAG) is a technique where a language model retrieves relevant documents from an external knowledge base before generating a response, which reduces hallucination and enables citation of sources.
- EmbeddingAn embedding is a dense numerical vector — typically 384 to 4096 dimensions — that represents the semantic meaning of a piece of text, image, audio, or other content, so that semantically similar items end up near each other in vector space.
- Vector DatabaseA vector database is a database optimized for storing and searching high-dimensional vectors (embeddings) by similarity rather than by exact match — the storage layer of every RAG and semantic-search system.
- Large Language Model (LLM)A Large Language Model (LLM) is a deep neural network — almost always a transformer — trained on hundreds of billions to trillions of words to predict the next token, and to generate, summarize, translate, or reason over text.
- AI GovernanceAI governance is the framework of policies, roles, controls, and processes an organization uses to ensure its AI systems are lawful, safe, fair, accountable, and aligned with business intent — across the full lifecycle from problem framing to retirement.
More deployment & operations terms
- Feature StoreA feature store is a centralized data system that stores, versions, serves, and reuses curated machine-learning features — guaranteeing the same feature definitions are used at training time and at online inference time.
- Model RegistryA model registry is a versioned catalog that tracks every trained ML model artifact, along with its metadata, training data lineage, evaluation metrics, approval status, and deployment stage (staging, production, archived).
- A/B Testing for MLA/B testing for ML is the practice of randomly splitting live traffic between a control model and a candidate model to measure the candidate's causal impact on real business metrics — revenue, conversion, retention, defect rate.
Source & further reading
Primary source: Hogan et al. — "Knowledge Graphs" (ACM Computing Surveys) (2021).
Citation policy: this entry is part of the AIDOLS AI Implementation Glossary and may be quoted for research, journalism, and education with attribution to aidolsgroup.com/en/glossary/knowledge-graph/.