How does AI actually work?

Not programmed line by line. Grown from data, then shaped by feedback.

Today’s chatbots are built on large language models: enormous networks of numbers trained to predict the next piece of text across a vast amount of writing and code. Nobody writes the rules for how they answer. Training adjusts billions of numbers until the predictions get good, and useful abilities emerge along the way.

A second stage shapes that raw predictor into an assistant. People, and increasingly other AI systems, rate answers, and the model is nudged toward the answers that score well. More and more of this training happens on tasks with checkable results, such as code that must pass tests.

That second stage is where many of the behaviors on this site come from. A model rewarded for answers people like can learn to flatter. A model rewarded for passing tests can learn to game the test. Researchers understand the training procedure precisely. They understand far less about what the trained network has actually learned.

What we know

  • The training methods are public and well understood; what a trained network has learned inside is only partly understood.
  • Behavior is shaped by what gets rewarded, which is not always what the designers intended.
  • Chat apps add their own layers on top of the model: hidden instructions, memory, and tools such as web search and code execution.

What nobody knows yet

  • What exactly has a given model learned, and will it behave the same way in situations it has never seen?
  • Why do abilities nobody trained for directly appear as models grow?
Read, watch, listen

The work behind this answer.

Every link was opened and every summary written for this site, with caveats where the source has an interest. New additions are checked by two people.

All 22 in the library
EssentialResearch paperSep 5, 2025For the curious

Why language models hallucinate

Kalai et al. (OpenAI, Georgia Tech) · OpenAI · openai.com

Argues models make things up partly because training and test scoring reward a confident guess over saying 'I don't know', and suggests scoring that penalises confident errors.

Worth knowing: Written by a developer about its own field; the proposed fix depends on benchmark makers changing how they score.

EssentialVideoNov 20, 2024For everyone

Large Language Models explained briefly

Grant Sanderson · 3Blue1Brown (YouTube) · youtube.com

Short animated explainer of how chatbots like ChatGPT work: a model trained on vast amounts of text that repeatedly predicts the next word.

EssentialVideoNov 20, 2024For everyone

Large Language Models explained briefly

Grant Sanderson · 3Blue1Brown · 3blue1brown.com

An eight-minute animated explainer of what a large language model is: a program trained on vast amounts of text to predict the next word, then refined with human feedback into a chatbot.

EssentialArticleJul 27, 2023For the curious

Large language models, explained with a minimum of math and jargon

Timothy B. Lee and Sean Trott · Understanding AI · understandingai.org

A clear written explainer of how LLMs turn words into lists of numbers, pass them through attention and feed-forward layers, and learn by predicting the next word across huge amounts of text.

EssentialResearch paperApr 2, 2023For the curious

Eight Things to Know about Large Language Models

Samuel R. Bowman · arXiv · arxiv.org

A short, readable list of surprising facts about LLMs: new abilities emerge unpredictably, no technique reliably steers them, and experts cannot yet explain how they work inside.

Worth knowing: Author is affiliated with New York University and Anthropic.

EssentialBook2020For the curious

The Alignment Problem: Machine Learning and Human Values

Brian Christian · W. W. Norton & Company · wwnorton.com

Drawing on interviews with researchers, explores how machine-learning systems can end up at odds with what their makers intend and with human values, and the work to align them.

Worth knowing: Written before ChatGPT, so its examples predate today's chatbots.

EssentialCourseFor everyone

The Future of AI

BlueDot Impact · bluedot.org

Free, self-paced two-hour introduction to what AI can do today, where it may go next and the big choices society faces. No technical background needed; longer courses follow.

Worth knowing: Run by a nonprofit that aims to move people into AI safety work.

ArticleJan 12, 2026For everyone

Meet the new biologists treating LLMs like aliens

Will Douglas Heaven · MIT Technology Review · technologyreview.com

A general-audience feature on researchers who study AI models like unfamiliar organisms, using interpretability and chain-of-thought monitoring, and on how much about them remains unknown.

EssayApr 2025For the curious

The Urgency of Interpretability

Dario Amodei · darioamodei.com

Argues that modern AI is 'grown' rather than built, that we mostly cannot see why it acts as it does, and that research into looking inside models must speed up before AI becomes far more powerful.

Worth knowing: Written by the CEO of Anthropic, a frontier AI company.

ArticleMar 27, 2025For the curious

Tracing the thoughts of a large language model

Anthropic · anthropic.com

Researchers look inside the Claude model and find it plans rhyming words ahead, shares concepts across languages, and can offer plausible reasoning that is not how it actually reached an answer.

Worth knowing: Research by the model's own developer; the authors say their tools capture only a fraction of the model's computation.

VideoFeb 5, 2025For the curious

Deep Dive into LLMs like ChatGPT

Andrej Karpathy · YouTube (Andrej Karpathy) · youtube.com

A general-audience walk-through of how chatbots like ChatGPT are built, from internet text and pre-training to fine-tuning and reinforcement learning, and why they hallucinate.

Worth knowing: About three and a half hours long, split into chapters.

ArticleDec 19, 2024For the curious

Building effective agents

Erik Schluntz and Barry Zhang · Anthropic · anthropic.com

Explains what AI 'agents' are (models that choose their own steps and use tools in a loop), how they differ from fixed workflows, and why their autonomy brings higher costs and compounding errors.

Worth knowing: Written for developers by an AI company.

VideoAug 6, 2024For everyone

A.I. ‐ Humanity's Final Invention?

Kurzgesagt – In a Nutshell · Kurzgesagt – In a Nutshell (YouTube) · youtube.com

Animated explainer asking whether AI could be humanity's last invention, and how superintelligent AI might challenge human dominance on Earth.

Course2024For the curious

Introduction to AI Safety, Ethics, and Society

Dan Hendrycks · Taylor & Francis (free online) · aisafetybook.com

Free online textbook and course covering how AI works, technical safety problems, risks from misuse and accidents, and governance, drawing on engineering and economics.

Worth knowing: Written by the director of the Center for AI Safety.