Skip to content

All topics / How LLMs Are Made

How a large language model is made, from raw text to chatbot

Follow one model through the whole factory: collecting and cleaning text, cutting it into tokens, months of next-token practice on thousands of chips, then the training that turns an autocomplete into a helpful assistant. Each lesson is a 6-minute animated drawing with a quick game. No maths, no code.

  • 24 lessons
  • 144 min
  • Free
  • No sign-up
Tomás · Training engineer at Vireo Labs

Hi, I'm Tomás. I help train language models at Vireo Labs. I'll walk you through every station of the line, from a messy pile of web pages to a model that answers questions, and show you where the hard choices are made.

01

The raw material

Where the text comes from, how it is cleaned and how it becomes numbers

  1. 1

    What is a large language model?

    A giant next-word predictor, built from text

    6 min
  2. 2

    Where the training text comes from

    Web crawls, books, code and conversations

    6 min
  3. 3

    Cleaning the data

    Removing duplicates, spam and private details

    6 min
  4. 4

    Tokens: how text becomes pieces

    Why a model reads "unbelievable" as three parts

    6 min
  5. 5

    Embeddings: words as points in space

    Similar meanings end up close together

    6 min
  6. 6

    Whose data is it?

    Copyright, consent and opting out

    6 min
02

Pretraining

The transformer, attention and months of guessing the next token

  1. 7

    The transformer

    The layered design behind every modern LLM

    6 min
  2. 8

    Attention

    How each word looks back at the words that matter

    6 min
  3. 9

    Guess the next token

    The one training game, played trillions of times

    6 min
  4. 10

    Learning from mistakes

    Loss, nudges and billions of tiny dials

    6 min
  5. 11

    Scaling up

    More data, more parameters, more chips

    6 min
  6. 12

    The base model

    A brilliant autocomplete that is not an assistant yet

    6 min
03

Becoming an assistant

Instructions, human feedback, reasoning, safety and tools

  1. 13

    Instruction tuning

    Teaching the model to follow requests

    6 min
  2. 14

    Learning from human feedback

    People compare two answers and pick the better one

    6 min
  3. 15

    Reward models

    A second model that scores answers

    6 min
  4. 16

    Learning to reason

    Thinking step by step on problems with checkable answers

    6 min
  5. 17

    Safety training

    Refusing harm, staying honest, admitting doubt

    6 min
  6. 18

    Tools and agents

    Search, code and actions in the world

    6 min
04

Testing and shipping

Benchmarks, red teams, smaller models and how a reply is generated

  1. 19

    Benchmarks and evals

    How a new model gets its report card

    6 min
  2. 20

    Red teaming

    Experts try to break the model before launch

    6 min
  3. 21

    Making models smaller

    Distillation and quantization

    6 min
  4. 22

    How a reply is generated

    One token at a time, with a dash of chance

    6 min
  5. 23

    Context windows and memory

    What the model can see at once, and what it forgets

    6 min
  6. 24

    Model cards and release

    What a responsible launch tells you

    6 min

How it works

  1. 01

    See it

    An animated drawing shows how the thing really works.

  2. 02

    Try it

    A short game makes you use it: spot, sort, switch, decide.

  3. 03

    Keep it

    Three takeaways and a badge for your sheet.

How LLMs Are Made glossary →

Questions people ask

Do I need to know maths or programming?

No. Every step is shown as an animated drawing with everyday examples. You will see what a token, a weight or a reward model is without a single formula.

How long does it take to train a large language model?

Pretraining a frontier model usually runs for weeks to months on thousands of specialised chips, after a long phase of collecting and cleaning data. The fine-tuning that turns it into an assistant comes on top.

Is this course free?

Yes. Every lesson is free, with no sign-up and no paywall.

How is this different from the AI Literacy course?

AI Literacy is about understanding and using AI well. This course goes behind the scenes and follows one model through every stage of how it is built, tested and released.