3.1 The Black Box

Text goes in, text comes out — but what's actually happening inside?

🎯 Core Goals

  • Introduce the LLM as an input/output black box.
  • Build curiosity about what happens inside with a predefined guess quiz.
  • Bridge to the sandwich model in 3.2.

Text goes in. Text comes out. That’s the whole interface — but what’s actually happening inside that box? Let’s find out.

👁️ Visuals & Interactives

💬
Your Message
Text In
📦
LLM
??? What's inside?
🤖
Reply
Text Out

What's actually happening inside that box?

📝 Key Concepts

  • The Black Box: From the outside, an LLM is simple — text in, text out. The chat interface hides all the machinery.
  • Next-Token Prediction: The LLM’s core job is to predict the most statistically likely next word/token, given everything before it. It does this repeatedly until the reply is complete.
  • Not a Search Engine: LLMs don’t look things up in real-time. They generate text from learned patterns — powerful, but also why they can confidently say things that are wrong.
  • The Interface Illusion: The chat app makes it look like a flowing conversation. What actually happens each turn? That’s what we explore next.

If it just predicts words… how does it “remember” your whole conversation? That’s the trick — every time you hit Send, something surprising happens under the hood. Let’s look at it next.

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