---
title: "Self-Study LLM"
description: "A router scores the experts for each token, and a sparse MoE block runs only the chosen ones. Build one, change the routing, then check expert load."
canonical_url: "https://fanout.sh/ai/lessons/llm-from-scratch-self-study-llm"
md_url: "https://fanout.sh/ai/lessons/llm-from-scratch-self-study-llm.md"
access: "pro-preview"
---

# Self-Study LLM

A router scores the experts for each token, and a sparse MoE block runs only the chosen ones. Build one, change the routing, then check expert load.

- Access: Fanout Pro (public preview)
- Module: LLM From Scratch

## A glimpse of Self-Study LLM

A model can own several small feed-forward networks and choose which ones process each token. Those networks are called experts. A router scores the experts for the current token, and a sparse mixture-of-experts block runs only the selected ones.

The word “expert” does not mean we assigned one network to mathematics and another to grammar. Their behavior is learned from training.

## Continue learning

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