Deep Dive into LLMs like ChatGPT

211 minutesAdvancedBuilderAndrej KarpathyChatGPT & LLMs

Andrej Karpathy. This is the clearest end-to-end explanation on YouTube of what an LLM actually is — pretraining, tokenization, SFT, RLHF, reasoning RL, tool use, hallucinations — at the level of detail an engineer needs to reason about model trade-offs. Watch it once and the "GPT-class vs. open-weights vs. reasoning model" decisions in the article stop feeling like brand choices and start feeling like training-recipe choices.

AI Expert note

Model names, pricing and capabilities change quickly. Use this for the decision pattern, then verify current model behavior before adopting it.

What you should get from this

Understand the modern LLM stack well enough to reason about tokens, training, tools and failures.

Watch or know first

Engineering background helps; no ML prerequisites, but budget for the three-and-a-half-hour runtime.

Last reviewed: May 18, 2026

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