What Is Mixture-of-Experts? The Breakthrough Architecture Powering Massive AI Models Like GPT, Mixtral, and Gemini

What is Mixture-of-Experts? This powerful architecture is the backbone of large-scale AI models like GPT, Mixtral, and Gemini. In this article, we explore Mixture-of-Experts (MoE) from a developer’s perspective—tracing its origins, understanding its routing logic, and analyzing how it optimizes compute while scaling model capacity. You'll learn how MoE selectively activates only a few expert networks per input token, dramatically reducing computation cost without sacrificing performance. Through intuitive analogies and technical breakdowns, we’ll walk through how gating networks, top-k routing, and modular feed-forward layers work in harmony to handle complex tasks efficiently. Whether you’re a machine learning engineer, AI researcher, or curious learner, this guide will equip you with foundational knowledge on one of the most transformative concepts in modern model architecture.