Definition
Episodic and semantic memory are two categories of long-term memory that AI agent designers borrow from cognitive psychology, where Endel Tulving drew the distinction in 1972. Episodic memory holds specific events situated in time and tied to the agent's own experience, while semantic memory holds decontextualized facts and concepts that are true regardless of when they were learned. Both sit in an agent's long-term store and are retrieved into the context window as needed.
Episodic memory in agents
For an AI agent, episodic memory records structured traces of past interactions: a timestamp, the user, the action taken, the conditions, and the outcome observed. Recalling "last time I tried this approach on this task, it failed for this reason" lets an agent learn from its own history and avoid repeating mistakes, a behaviour sometimes called experience-following.
Semantic memory in agents
Semantic memory instead stores stable knowledge independent of any single episode: domain facts, product specifications, user preferences, and definitions. It answers "what is true" rather than "what happened to me." In practice the two interact, just as Tulving later argued they do in humans; an agent often consults general semantic knowledge while interpreting a specific episodic record.
Distinguishing the two helps designers decide what to persist and how to retrieve it within an agent's broader memory system. Holding both stores on hardware you control is central to sovereign AI, since they accumulate a detailed model of you and your work. D-Central documents these memory types for self-hosted deployments.
In Simple Terms
Episodic and semantic memory are two categories of long-term memory that AI agent designers borrow from cognitive psychology, where Endel Tulving drew the distinction in…