What Is Retrieval-Augmented Generation (RAG)?
Retrieval-augmented generation (RAG) is a technique in which an AI system first retrieves relevant information from a defined source, your documents, knowledge base, or database, and then generates its answer using that retrieved material, rather than relying only on what the model memorized during training.
The flow has two steps. When you ask a question, the system searches your content for the most relevant passages (retrieval), then feeds those passages to a large language model along with your question, instructing it to answer from that material (generation). Good RAG systems also cite which documents each answer came from.
Why it matters at work
RAG solves the two biggest problems with using a raw LLM at work. First, the model doesn’t know your business, your policies, products, pricing, or project history aren’t in its training data. RAG feeds it that knowledge on demand, without the cost and complexity of retraining a model. Second, it reduces guessing: because the model answers from provided text and can cite its sources, answers are more verifiable and hallucinations are less frequent, though not eliminated, since the model can still misread or over-extrapolate from what it retrieved. Retrieval quality is the usual weak point: if the search step surfaces the wrong document (or an outdated one), the answer will be confidently wrong with a citation attached.
RAG is the architecture behind most “chat with your documents” products, enterprise AI search, and AI customer-support bots, and it’s effectively how AI answer engines like Perplexity and Google’s AI Overviews work, retrieving live web pages and generating cited answers from them.
A work example
An operations team loads its HR policies, IT runbooks, and onboarding docs into a RAG-based assistant. A new hire asks, “How do I expense a client dinner?” The system retrieves the expense-policy section, and the model answers with the actual limits and the approval steps, linking the source page, instead of inventing a generic policy that sounds right.
Related terms
- Large language model, the generation engine RAG builds on
- Hallucination, the failure mode RAG is designed to reduce
FAQ
What problem does RAG solve? It lets a model answer from your current, private documents rather than only its training data, which reduces hallucinations and stale answers and lets responses cite checkable sources.
Is RAG better than fine-tuning for company knowledge? Usually, yes. RAG keeps knowledge current by updating documents instead of retraining, and it can show where an answer came from. Fine-tuning is better for teaching style and task behavior than facts.