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References

The full picture, once you've used a piece of it

References are most useful after you've already needed them. Build something first, then come back to a reference to fill in the corners.

General

HTML Headings

h1 through h6 are the page’s table of contents. Use them for structure, never for size — that’s what CSS is for.

HTML Headings

h1–h6 are instances of HTMLHeadingElement. They take no special attributes — only the global set and ARIA — but there’s real depth in how they form the document outline and what you can do with them from JavaScript.

HTML Headings

Headings, distilled to what you must remember.

HTML Headings

Everything about h1–h6 you’d look up mid-task, with no preamble.

CSS card — cheatsheet

The box-model card at a glance — the handful of properties that do the work, ready to copy.

CSS card — reference

One-liner reference for the card project’s properties — scan, copy, and open the live example.

Arrays — reference

Arrays in JavaScript: indexing, mutation, iteration, the methods that survive the test of time, and the ones that do not.

Introduction to Svelte

Svelte is a web technology. Compile-time reactivity — no virtual DOM.

Introduction to Three.js

Three.js is a web technology. WebGL 3D for the browser, made tractable.

Introduction to Framer Motion

Framer Motion is a web technology. Production-ready animation for React.

Introduction to PHP

PHP still runs a huge slice of the web — from WordPress to Wikipedia — and modern PHP is fast and pleasant.

Introduction to Tailwind

Tailwind is a web technology. Utility-first CSS you compose in markup.

Introduction to Sass

Sass is a web technology. CSS with variables, nesting, and mixins.

Introduction to Vite

Vite is a web technology. Instant dev server and lightning builds.

Introduction to Webpack

Webpack is a web technology. The configurable module bundler.

Introduction to C

C is the language the rest of computing is built on — small, fast, and unforgiving, it maps almost directly onto how the machine actually works.

Introduction to Nim

Nim reads like Python but compiles to small, fast native binaries with no runtime dependency.

Introduction to Assembly

Assembly is a programming language. Talk to the processor in its own instructions.

Introduction to Java

Java is the workhorse of enterprise software — write once, run anywhere on the Java Virtual Machine.

Introduction to C#

C# is Microsoft’s modern, multi-paradigm language — the heart of .NET and a joy to write at scale.

Introduction to Kotlin

Kotlin is a concise, null-safe language for the JVM — and Google’s preferred language for Android.

Introduction to Swift

Swift is Apple’s fast, safe, modern language — the way to build for iPhone, iPad, Mac, and beyond.

Introduction to Scala

Scala fuses object-oriented and functional programming on the JVM — expressive, powerful, and built for scale.

Introduction to Dart

Dart is the client-optimised language behind Flutter — one codebase, every screen.

Introduction to Objective-C

Objective-C is a programming language. The classic language of the Apple platforms.

Introduction to Groovy

Groovy is a programming language. Dynamic scripting that supercharges the JVM.

Introduction to Crystal

Crystal is a programming language. Ruby-like syntax compiled to native speed.

Introduction to Fortran

Fortran is a programming language. The granddaddy of high-performance scientific computing.

Introduction to Ruby

Ruby was designed for developer happiness — readable, expressive, and a delight for building things fast.

Introduction to Lua

Lua is a tiny, blazing-fast scripting language designed to be embedded inside other programs.

Introduction to Perl

Perl is the original swiss-army chainsaw of text processing — powerful, pragmatic, and still everywhere on Unix systems.

Introduction to Bash

Bash is the shell on nearly every Linux and Mac — the glue that automates everything in a terminal.

Introduction to PowerShell

PowerShell is a shell that passes objects, not just text — automation that understands your data.

Introduction to Haskell

Haskell is purely functional and lazily evaluated — a language that will change how you think about code.

Introduction to Clojure

Clojure is a modern Lisp for the JVM — minimal syntax, immutable data, and a powerful approach to state.

Introduction to F#

F# is a programming language. Functional-first .NET with pragmatic power.

Introduction to Elixir

Elixir builds wildly concurrent, fault-tolerant systems on the battle-tested Erlang VM.

Introduction to Erlang

Erlang is a programming language. Telecom-grade concurrency and nine-nines uptime.

Introduction to OCaml

OCaml is a programming language. Industrial-strength functional programming.

Introduction to R

R is the language built by statisticians, for statistics — the go-to for data analysis and visualisation.

Introduction to Julia

Julia delivers C-like speed with Python-like ease — built from the ground up for numerical and scientific computing.

Introduction to MATLAB

MATLAB is a programming language. Numerical computing and engineering, batteries included.

Introduction to Solidity

Solidity is the language of smart contracts — programs that run on the Ethereum blockchain.

Introduction to COBOL

COBOL is a programming language. Still running the world’s financial systems.

Introduction to Visual Basic

Visual Basic is a programming language. An approachable .NET language with a long legacy.

Introduction to Node.js

Node.js is a backend technology. JavaScript on the server, event-driven I/O.

Introduction to Express

Express is a backend technology. The minimal, unopinionated Node web framework.

Introduction to NestJS

NestJS is a backend technology. Structured, batteries-included Node framework.

Introduction to Django

Django is a backend technology. Python framework with batteries included.

Introduction to FastAPI

FastAPI is a backend technology. Type-driven, async Python APIs, fast.

Introduction to Spring

Spring is a backend technology. The Java framework that runs the enterprise.

Introduction to Ruby on Rails

Ruby on Rails is a backend technology. Convention over configuration, full-stack Ruby.

Introduction to Laravel

Laravel is a backend technology. The PHP framework for artisans.

Introduction to REST

REST is a backend technology. Resource-oriented HTTP API design.

Introduction to GraphQL

GraphQL is a backend technology. Ask for exactly the data you need.

Introduction to gRPC

gRPC is a backend technology. Contract-first, binary, fast service calls.

Introduction to WebSockets

WebSockets is a backend technology. Full-duplex, real-time connections over one socket.

Introduction to Sessions

Sessions is a backend technology. Server-side login state, done right.

Introduction to SQL

SQL is the language every relational database speaks — the single most transferable data skill you can learn.

Introduction to PostgreSQL

PostgreSQL is a data technology. The relational database that does it all.

Introduction to MySQL

MySQL is a data technology. The ubiquitous open-source relational DB.

Introduction to SQLite

SQLite is a data technology. A whole SQL database in a single file.

Introduction to MongoDB

MongoDB is a data technology. Document storage with a flexible schema.

Introduction to Redis

Redis is a data technology. In-memory data store for speed and queues.

Introduction to Prisma

Prisma is a data technology. Type-safe ORM with a schema-first model.

Introduction to Drizzle

Drizzle is a data technology. SQL-first, fully typed TypeScript ORM.

Introduction to Machine Learning

Machine Learning is a AI/ML technology. Models that learn patterns from data.

Introduction to Deep Learning

Deep Learning is a AI/ML technology. Neural nets that power modern AI.

Introduction to Neural Networks

Neural Networks is a AI/ML technology. The building block under deep learning.

Introduction to PyTorch

PyTorch is a AI/ML technology. Dynamic, Pythonic deep-learning framework.

Introduction to TensorFlow

TensorFlow is a AI/ML technology. End-to-end ML platform at scale.

Introduction to LangChain

LangChain is a AI/ML technology. Compose LLM apps from reusable parts.

Introduction to Prompting

Prompting is a AI/ML technology. Direct a model to do the work you want.

Introduction to RAG

RAG is a AI/ML technology. Ground a model in your own documents.

Introduction to Agents

Agents is a AI/ML technology. Models that call tools and take action.

Introduction to Fine-tuning

Fine-tuning is a AI/ML technology. Specialise a base model on your data.

Introduction to React Native

React Native is a mobile technology. Native apps from one React codebase.

Introduction to Flutter

Flutter is a mobile technology. Pixel-perfect cross-platform from Dart.

Introduction to Expo

Expo is a mobile technology. The fastest way to ship React Native.

Introduction to Android

Android is a mobile technology. Build for the world’s biggest platform.