LLM Training Stages: Pre-training, Mid-training, SFT, RL, and DPO
What actually happens at each stage of training a large language model — what data, what objective, what the model learns, and why the stages are ordered the way they are.
What actually happens at each stage of training a large language model — what data, what objective, what the model learns, and why the stages are ordered the way they are.
What actually happens at each stage of training a large language model — what data, what objective, what the model learns, and why the stages are ordered the way they are.
Training a helpful, harmless, honest LLM requires three sequential stages that each build on the previous one. Here's how SFT, reward modeling, and RL fit together as a system — and where each stage can fail.
Supervised fine-tuning teaches a model to imitate. Reinforcement learning teaches it to optimize. The difference turns out to matter enormously.
Human annotation doesn't scale to the data volumes modern alignment requires. Synthetic data — generated by LLMs, filtered, and refined — has become the dominant approach. Here's how it's done and where it breaks down.
Training a helpful, harmless, honest LLM requires three sequential stages that each build on the previous one. Here's how SFT, reward modeling, and RL fit together as a system — and where each stage can fail.
Supervised fine-tuning teaches a model to imitate. Reinforcement learning teaches it to optimize. The difference turns out to matter enormously.
Human annotation doesn't scale to the data volumes modern alignment requires. Synthetic data — generated by LLMs, filtered, and refined — has become the dominant approach. Here's how it's done and where it breaks down.