Architectures · advanced · concept 70 of 176
Mixture-of-Experts (MoE)
A Transformer variant where each layer holds many parallel expert subnetworks and a router activates only a few per token. This decouples total parameter count from per-token compute, so models can grow far larger without proportional cost. Many frontier and open-weight LLMs use MoE.
Key terms
RouterSparse activationExpertLoad balancingActive parameters
Learn these first
Where you meet it in the real world
Frontier LLMs, cost-efficient serving, large open-weight models
Videos
▶ Stanford CS336 Language Modeling from Scratch | Spring 2025 | Lecture 4: Mixture of experts ↗
Stanford Online · YouTube
▶ What is Mixture of Experts? ↗
IBM Technology · YouTube
Guides and articles
Courses, papers, and more