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Sreekar Reddy
Sreekar Reddy

Posted on • Originally published at sreekarreddy.com

📚 RAG Explained Like You're 5

An open-book exam for AI

Day 3 of 149

👉 Full deep-dive with code examples


The Open-Book Exam

Imagine two types of exams:

Closed-book exam:

  • You mostly rely on what's in your head
  • If you didn't memorize it, you're stuck

Open-book exam:

  • You can look things up
  • Reference your notes
  • Find the specific answer

RAG gives AI an open-book exam!


The Problem

LLMs (like ChatGPT) have knowledge frozen at training time:

  • Don't know recent events
  • Can't access your private documents
  • Sometimes make things up (hallucinate)

How RAG Works

Retrieval-Augmented Generation:

  1. Question comes in → "What's our refund policy?"
  2. Retrieval → Search your documents for relevant info
  3. Augment → Add that info to the prompt
  4. Generate → AI answers using the found documents
User: "What's the refund policy?"
     ↓
[Search company docs]
     ↓
Found: "Refunds within 30 days with receipt..."
     ↓
AI: "Based on your policy, refunds are allowed within 30 days..."
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Why It's Powerful

  • ✅ AI can answer about YOUR data
  • ✅ Answers are grounded in real documents
  • ✅ Reduces hallucinations
  • ✅ Can stay up-to-date (as your docs change, answers can change)

In One Sentence

RAG lets AI look up information before answering, like having notes during a test.


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