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RAG: AI that answers from your documents

Know how an AI app finds the right page in your documents, what it sends the model, and where the answer can still go wrong.

How retrieval-augmented generation works, step by step, on one washer manual: preparing the documents, the search that finds the right page, the message the model receives and the answer you can check. Then the 3 ways to build one, tested side by side.

The lessons, in order

  1. What is RAG? How AI answers from your own documents

    9 min read · 11 chapters · 11 short clips

    RAG, retrieval-augmented generation, is how an AI app answers from documents the model never read. It finds the right pages, adds them to your question and has the model answer from them. This lesson follows one question through the 4 steps, shows the message the AI really receives, and names the 3 ways it still goes wrong.

    1. A washer error that no AI could answer1:29
    2. RAG is an open-book exam1:15
    3. Why not paste the whole manual?1:27
    4. Step 1: prepare the documents1:28
    5. Step 2: retrieve the closest pages1:16
    6. Step 3: the message the AI really receives1:14
    7. Step 4: an answer you can check1:21
    8. Where you already use RAG1:00
    9. 3 ways RAG still gets it wrong1:20
    10. The 4 steps, and a quick test59 s
    11. RAG makes AI informed, not smarter48 s
  2. How RAG search works: embeddings, hybrid search, reranking

    11 min read · 10 chapters · 6 short clips

    How does a RAG app find the right page when your words are not the document's words? This lesson runs one washer manual through a real search, from keyword search to embeddings and cosine similarity, shows where meaning search is blind, and tests the 3 fixes builders use, hybrid search, context notes and a reranker, with the scores we got.

    1. The water just sits there1:11
    2. Search by words1:38
    3. A map of meaning1:39
    4. How close is close?1:32
    5. Where the map comes from1:04
    6. Where meaning search is blind1:36
    7. Cutting the cards
    8. A second opinion
    9. The search, rebuilt
    10. Bad answers often start with bad search
ToolSize the index for your documentsHow many chunks and vectors your documents make, and the memory and disk their index needs.

Every lesson has the same 4 parts

  1. Watch

    The full video, and a short clip at each chapter if you only want that part.

  2. Read

    The longer explanation, with the sums worked out and a link to the source of every fact.

  3. Try it

    An experiment you run in your own AI assistant, with prompts to copy and what to look for.

  4. Check

    3 questions that put the idea in a new situation, each with the reason for its answer.