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title: "Machine Learning Concepts"
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A four-level handbook
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# Machine learning, from first principles to deployed systems.
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This handbook explains the mechanisms behind modern machine learning without asking readers to choose between intuition and technical precision. Each chapter develops one idea through explanation, mechanics, mathematics and code, and its consequences for research or production systems.
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[Start with Chapter 1 →](01-what-is-machine-learning.html){.hero-primary}
[Browse the concepts appendix](appendix-concepts.html){.hero-secondary}
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## A way through a large field
The field is easier to follow when its dependencies are visible. The first part establishes how a model makes a prediction and how training changes its parameters. The next sections develop neural networks, representations and transformers before turning to large-language-model training, reasoning methods, multimodal architectures, deployment and responsible use.
<div class="pathway-plot" role="img" aria-label="A pathway from foundations through neural networks and transformers to language models, reasoning, multimodal systems, and deployment">
<div class="pathway-step pathway-foundations"><span>01</span><strong>Foundations</strong><small>models, loss, optimisation</small></div><div class="pathway-link"></div>
<div class="pathway-step pathway-networks"><span>02</span><strong>Neural networks</strong><small>layers, gradients, regularisation</small></div><div class="pathway-link"></div>
<div class="pathway-step pathway-transformers"><span>03</span><strong>Transformers</strong><small>vectors, attention, tokens</small></div><div class="pathway-link"></div>
<div class="pathway-step pathway-language"><span>04</span><strong>Language models</strong><small>pretraining, tuning, retrieval</small></div><div class="pathway-link"></div>
<div class="pathway-step pathway-systems"><span>05</span><strong>Reasoning & systems</strong><small>inference, deployment, safety</small></div>
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## Four levels, one argument
Every chapter begins with the question the concept solves. The same concept is then developed at progressively greater technical depth. Readers can stop at the level that matches their purpose or continue through the full sequence.
<div class="levels-grid">
<section class="level-card level-one"><p class="level-number">Level 1</p><h3>Intuition</h3><p>What the concept is, what problem it addresses, and what would fail without it.</p></section>
<section class="level-card level-two"><p class="level-number">Level 2</p><h3>Mechanics</h3><p>The steps, information flows and design choices that make the method work.</p></section>
<section class="level-card level-three"><p class="level-number">Level 3</p><h3>Mathematics & code</h3><p>The notation, objective functions and compact implementations behind the mechanism.</p></section>
<section class="level-card level-four"><p class="level-number">Level 4</p><h3>Research & systems</h3><p>What changes at scale, where evidence is limited, and how the method is used in practice.</p></section>
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## What the book covers
<div class="coverage-grid">
<a class="coverage-card" href="01-what-is-machine-learning.html"><span class="coverage-index">Part I</span><h3>Learning from data</h3><p>Predictions, losses, gradient descent and backpropagation.</p><span>Chapters 1–4 →</span></a>
<a class="coverage-card" href="05-artificial-neuron.html"><span class="coverage-index">Part II</span><h3>Neural networks</h3><p>Layers, activation functions, generalisation and efficient training.</p><span>Chapters 5–15 →</span></a>
<a class="coverage-card" href="16-vectors-tensors-representations.html"><span class="coverage-index">Part III</span><h3>Representations & transformers</h3><p>Embeddings, sequence modelling, attention and tokenisation.</p><span>Chapters 16–24 →</span></a>
<a class="coverage-card" href="25-next-token-prediction.html"><span class="coverage-index">Part IV</span><h3>Large language models</h3><p>Next-token prediction, pretraining, inference, tuning and retrieval.</p><span>Chapters 25–34 →</span></a>
<a class="coverage-card" href="35-what-makes-a-reasoning-model.html"><span class="coverage-index">Part V</span><h3>Reasoning models</h3><p>Evaluation, test-time compute, search, reinforcement learning and distillation.</p><span>Chapters 35–42 →</span></a>
<a class="coverage-card" href="43-mixture-of-experts-models.html"><span class="coverage-index">Part VI</span><h3>Architectures & deployment</h3><p>Mixture-of-experts, vision, diffusion, multimodality, monitoring and safety.</p><span>Chapters 43–49 →</span></a>
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<div><p class="book-eyebrow">Reference tool</p><h2>Find a concept without losing its context.</h2><p>The appendix collates the book’s core concepts and distinctions, with links back to the chapters where each one is developed.</p></div>
<a class="hero-primary" href="appendix-concepts.html">Open the appendix <span aria-hidden="true">→</span></a>
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## How to use the handbook
Read the chapters in order if the mechanisms are new to you: later chapters assume the conceptual sequence established earlier. If you already know the basics, use the table of contents to enter at the relevant part, then use the linked concepts appendix to recover any prerequisite. Code examples stay deliberately small. Their purpose is to expose the operation that a library would otherwise hide.