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Large language models

Learn what happens between a prompt and a dependable result.

Understand models, context, retrieval, tools, agents, validation, and runtime decisions—and see how those pieces come together in real LLM applications.

Build useful AI

See the system behind the answer

Knowing what an LLM can do is only the beginning. LearnLLMFast connects model fundamentals with prompting, RAG, agents, evaluation, and engineering so you can turn AI capabilities into useful applications.

Experience behind the lessons

LearnLLMFast Team

LearnLLMFast Team

Joe Chang

Joe Chang brings more than 20 years of software engineering experience across startups, research, international banking and FinTech, entrepreneurship, and production systems. A physics graduate of New York University who learned deep learning from Yann LeCun, he has taught more than 1,000 students across machine learning, deep learning, computer vision, reinforcement learning, and large language models. He has also worked with universities and government programs on AI engineering education.

  • Understand modern model architectures. Learn how attention, transformers, dense and sparse computation, mixture-of-experts designs, and other architectural ideas shape capability, efficiency, and model behavior.
  • Follow the full LLM training pipeline. Connect pretraining, supervised fine-tuning, preference learning, reinforcement-learning fine-tuning, alignment, and post-training into one picture of how modern models are created.
  • Build agentic AI that can plan and act. Learn how LLMs choose tools, decompose goals, maintain state, make decisions, and coordinate multi-step work across an execution loop.
  • Position yourself for high-paying AI work. Build knowledge that carries into LLM engineering, AI research, model training, application development, technical interviews, and the rapidly expanding market for people who understand modern AI deeply.
  • Stay close to the cutting edge of AI. Learn the ideas behind new model architectures, training methods, reasoning techniques, and research directions while the field is still moving quickly.

Learning paths

Choose where to start

Browse tutorials by topic so you can move from basic concepts to practical LLM projects.

absolute beginner
16 articles

LLM Basics

Look inside an LLM: tokens, context, transformers, next-token prediction, training, inference, fine-tuning, and the stages that shape model behavior.

Go learning path
beginner
14 articles

Prompting Fundamentals

Turn intent into clear instructions with message roles, examples, templates, structured outputs, generation settings, and systematic prompt debugging.

Go learning path
beginner
10 articles

Using AI Tools

Choose how you want to work with AI across ChatGPT, Gemini, local and open models, multimodal systems, and connected applications.

Go learning path
intermediate
19 articles

RAG and Agents

Give LLM applications evidence and actions with embeddings, retrieval, reranking, citations, tools, agents, memory, and controlled loops.

Go learning path
intermediate
10 articles

LLM Applications and Careers

Find where LLMs create real value in coding, business, education, projects, products, and careers—and choose use cases worth building.

Go learning path
intermediate
7 articles

LLM Safety and Security

Set trust boundaries around sensitive data, untrusted instructions, retrieved content, agent permissions, and consequential actions.

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intermediate
11 articles

LLM Evaluation and Reliability

Turn “looks good” into measured behavior with test cases, retrieval checks, regression testing, observability, evidence analysis, and failure triage.

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intermediate
8 articles

LLM Application Engineering

Move from demo to working system with validation, routing, caching, batching, request lifecycles, and practical application workflows.

Go learning path

Featured tutorials

Start with the essentials

These beginner tutorials explain the core ideas before you write larger programs.

A breathtaking sunrise over a vast mountainous landscape with clear skies.
intermediate
9 min read

What Are LLM Agents?

An LLM agent is not a smarter chatbot. It is a goal-driven system that uses a language model as its brain, then loops through action and observation until…

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High-tech laboratory equipment with computer system in lab setting.
absolute beginner
7 min read

What Is a Large Language Model?

A large language model is a pattern-prediction engine for language: it learns how words and ideas tend to follow one another, then uses that fluency to…

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Latest

Recently updated tutorials

Fresh and improved lessons from the tutorial library.

A breathtaking view of a desert landscape with a vibrant sunset illuminating the horizon.
beginner
11 min read

AI Tools Practice Exercises

Reading about AI tools builds recognition, not skill. Skill comes from running the tool, inspecting the output, and making one small change to see what…

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A dynamic top view of ocean waves and sea foam demonstrating nature's power and beauty.
beginner
8 min read

Choosing an AI Tool

You have three tabs open. ChatGPT in one, Claude in another, Gemini in the third. You paste the same question into all three, and you get three different…

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