Mechanisms that allow AI models to retain and recall information beyond a single conversation. This includes in-context memory (using the context window), external memory (RAG, vector databases), persistent conversation memory (remembering user preferences across sessions), and working memory (maintaining state during multi-step agent tasks). Memory is what makes AI feel like a collaborator rather than a stateless tool.
Why it matters
Without memory, every AI conversation starts from zero. You repeat your preferences, re-explain your codebase, re-describe your project. Memory is what turns a chatbot into an assistant — and it's one of the hardest problems to solve well, balancing relevance, privacy, staleness, and storage costs.