Key Concepts | Zep Documentation

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Zep is a context engineering platform that systematically assembles personalized context—user preferences, traits, and business data—for reliable agent applications. Zep combines Graph RAG, agent memory, and context assembly capabilities to deliver comprehensive personalized context that reduces hallucinations and improves accuracy.

Concept	Description	Docs
Knowledge Graph	Zep’s unified knowledge store for agents. Nodes represent entities, edges represent facts/relationships. The graph updates dynamically in response to new data.	Docs
Zep’s Context Block	Optimized string containing a user summary and facts from the knowledge graph most relevant to the current thread. Also contains dates when facts became valid and invalid. Provide this to your chatbot as “memory”.	Docs
Fact Invalidation	When new data invalidates a prior fact, the time the fact became invalid is stored on that fact’s edge in the knowledge graph.	Docs
JSON/text/message	Types of data that can be ingested into the knowledge graph. Can represent business data, documents, chat messages, emails, etc.	Docs
Custom Entity/Edge Types	Feature allowing use of Pydantic-like classes to customize creation/retrieval of entities and relations in the knowledge graph.	Docs
Graph	Represents an arbitrary knowledge graph for storing up-to-date knowledge about an object or system. For storing up-to-date knowledge about a user, a user graph should be used.	Docs
User Graph	Special type of graph for storing personalized memory for a user of your application.	Docs
User	A user in Zep represents a user of your application, and has its own User Graph and thread history.	Docs
Threads	Conversation threads of a user. By default, all messages added to any thread of that user are ingested into that user’s graph.	Docs
`graph.add` & `thread.add_messages`	Methods for adding data to a graph and user graph respectively.	Docs Docs
`graph.search` & `thread.get_user_context`	Low level and high level methods respectively for retrieving from the knowledge graph.	Docs Docs
User Summary Instructions	Customize how Zep generates entity summaries for users in their knowledge graph. Up to 5 custom instructions per user to guide summary generation.	Docs
Agentic Tool	Use Zep’s memory retrieval methods as agentic tools, enabling your agent to query for relevant information from the user’s knowledge graph.	Docs