# The Missing Manual > A free, text-first library of the real-world knowledge nobody teaches developers. > Every guide is plain Markdown, laddered from "what this actually is" to advanced. Any guide page also serves Markdown - send `Accept: text/markdown`. ## Machine-readable entry points - [llms.txt](https://themissingmanual.dev/llms.txt) - concise site index - [llms-full.txt](https://themissingmanual.dev/llms-full.txt) - full content index - [MCP server](https://themissingmanual.dev/mcp) - Model Context Protocol (Streamable HTTP, JSON-RPC 2.0) - [MCP server card](https://themissingmanual.dev/.well-known/mcp/server-card.json) - [API catalog](https://themissingmanual.dev/.well-known/api-catalog) - RFC 9727 linkset - [OpenAPI](https://themissingmanual.dev/openapi.json) - [Sitemap](https://themissingmanual.dev/sitemap.xml) ## Categories - [Logic](https://themissingmanual.dev/categories/logic) - Clear reasoning from the ground up - true/false, if-then, proof, and spotting bad arguments. The thinking that sits under all code and math. - [Mathematics](https://themissingmanual.dev/categories/mathematics) - The language reality is written in - sets, numbers, probability, and more - taught from intuition, for anyone who was told they're 'bad at math'. - [Physics](https://themissingmanual.dev/categories/physics) - How the physical world really works, in plain language - motion, energy, light, and the genuinely strange rules of the quantum world. The 'why' beneath the machine. - [Operating Systems](https://themissingmanual.dev/categories/operating-systems) - Windows, macOS, and Linux - what they're really doing under the hood, from first login to power user. - [Hardware](https://themissingmanual.dev/categories/hardware) - How the machine is actually built and talks to itself - from the chip to the device on your desk. - [Networking](https://themissingmanual.dev/categories/networking) - How the internet really works, and how to design networks that hold up - from your home router to the enterprise. - [Programming Concepts](https://themissingmanual.dev/categories/programming-concepts) - The ideas under every language - how code runs, data structures, async, memory, big-O, and choosing the right tool. - [Algorithms](https://themissingmanual.dev/categories/algorithms) - The classic algorithms every developer meets - searching, sorting, recursion, trees, graphs, and dynamic programming - taught from intuition, run in your browser, and shown side by side across languages. - [Programming Languages](https://themissingmanual.dev/categories/programming-languages) - Python, JavaScript, TypeScript, Java, C#, Go, and Rust - each language end to end, from zero to advanced. - [Web Fundamentals](https://themissingmanual.dev/categories/web-fundamentals) - HTML, CSS, and how the browser actually works - the web platform itself, learned properly before any framework touches it. - [Frontend](https://themissingmanual.dev/categories/frontend) - The modern client side - React, Next, Vue, Svelte, Angular, and the ideas they all share: components, state, rendering, and shipping interfaces users actually feel. - [Frameworks & Libraries](https://themissingmanual.dev/categories/frameworks) - Django, FastAPI, Spring Boot, and friends - the big backend frameworks and libraries, each tied to its language. - [Version Control](https://themissingmanual.dev/categories/version-control) - Git and friends: what they actually do, and how to stay calm when they break. - [Debugging & Troubleshooting](https://themissingmanual.dev/categories/debugging) - Reading the error, finding the real cause, and fixing it calmly instead of guessing. - [Testing](https://themissingmanual.dev/categories/testing) - Unit, integration, end-to-end, and load tests - plus TDD/BDD - that actually catch the bug. - [Databases](https://themissingmanual.dev/categories/databases) - Schemas, queries, and the production lessons that come with them. - [Data & Analytics](https://themissingmanual.dev/categories/data-analytics) - Data pipelines, engineering, BI, and the ML basics - turning raw data into answers you trust. - [APIs & Integration](https://themissingmanual.dev/categories/apis) - REST, GraphQL, gRPC, webhooks, and message queues - how systems actually talk to each other. - [Architecture](https://themissingmanual.dev/categories/architecture) - Designing systems that survive contact with real load and real teams. - [DevOps](https://themissingmanual.dev/categories/devops) - CI/CD, automation, and infrastructure as code - shipping safely and repeatedly. - [Infrastructure & Cloud](https://themissingmanual.dev/categories/infrastructure) - Servers, containers, and cloud platforms - where your code actually runs. - [Performance](https://themissingmanual.dev/categories/performance) - Finding the slow thing, and the tools that show you where it hides. - [Security](https://themissingmanual.dev/categories/security) - The threats, the defaults, and the habits that keep you out of the news. - [AI & Machine Learning](https://themissingmanual.dev/categories/ai-ml) - Models, training, and putting AI into real products - without the hype or the hand-waving. - [Working with AI](https://themissingmanual.dev/categories/working-with-ai) - Practical AI for everyone, not just ML engineers - prompting, agents, CLIs, MCP, skills and plugins, context and loop engineering, and getting real work done with AI. The hype-free user's manual. - [No-Code & Automation](https://themissingmanual.dev/categories/no-code) - Build apps and automate work without (much) code - Zapier, Make, n8n, Airtable, Retool, and the enterprise low-code platforms. For founders, ops, analysts, and anyone who'd rather ship than wait for engineering. - [Tools & Workflow](https://themissingmanual.dev/categories/tooling) - The tools a job expects you to already know - migrations, build systems, message queues, CI/CD, containers, cloud, auth, and observability - each explained for the day you have to use it. - [Projects](https://themissingmanual.dev/categories/projects) - Build real things end to end - small projects you follow step by step, with working code you can run in the browser or on your machine. The fastest way to make everything else stick. - [Working as a Developer](https://themissingmanual.dev/categories/working-as-a-developer) - The human side of the job nobody puts in a syllabus - code review, reading someone else's mess, asking good questions, surviving your first on-call, and interviews that don't feel like hazing. - [Practice](https://themissingmanual.dev/categories/practice) - Hands-on lessons in a three-panel coding playground - read the task, write real SQL, JavaScript, or Python, run it in your browser, and get checked instantly.