After this lesson, you will be able to: Understand what a JavaScript framework is, why React became the dominant UI library, why Next.js became the framework most teams pair with React in 2025, and how the rest of this subtrack will take you from zero to deploying full-stack apps.
React is the library every frontend job posting expects. Next.js is the framework most teams wrap React in. Together they're behind almost every modern web app you use — Stripe's dashboard, GitHub's UI, the OpenAI and Anthropic consoles, every Vercel-built site. This free intro lesson explains why this stack won, what each piece actually does, and what the rest of the subtrack will teach you. By the end you'll be able to name the parts and explain why a hiring manager cares.
This is a free introductory lesson. No purchase required.
A library gives you tools and lets you decide how to assemble them. A framework gives you the assembly. React is a UI library — it handles drawing components and reacting to state, and leaves everything else (routing, data fetching, deployment, bundling) to you. That worked in 2015 when apps were small. In 2025, gluing twenty libraries together yourself is overhead nobody pays for. Frameworks like Next.js wrap React and decide all the boring questions for you so you can focus on the actual product.
Three reasons React beat its rivals and stayed on top. (1) **Component model.** You describe your UI as small reusable pieces. Each component owns its state and rendering. When the state changes, the component re-renders, and React figures out the minimal DOM updates. (2) **Hooks (since 2019).** A clean, function-first way to use state and side effects without class components. Hooks are what made React feel modern again and what every job posting expects you to know. (3) **Ecosystem.** Every UI library you'd want — design systems, charts, animations, forms — has a React version. Job market follows.
React alone has no opinion on routing, server-side rendering, or where API code lives. Next.js fills those in. With Next, you get: **File-based routing** — drop a file in `app/blog/[slug]/page.tsx` and that URL exists; no router config required. **Server-side rendering (SSR) and static generation (SSG)** — your pages can be pre-rendered for fast loads and SEO without you wiring anything up. **React Server Components** — fetch data directly inside a component, on the server, with no extra API layer. Reduces JavaScript shipped to the browser. **API routes** — drop a `route.ts` file and you have a backend endpoint. **Edge runtime** — run code on Vercel's global edge network for low latency. All of this without leaving the React mental model.
Companies that ship Next.js in production today include Stripe (Dashboard, Atlas, Issuing), GitHub (Copilot pages and several account flows), the OpenAI and Anthropic consoles, Notion, Loom, Hashnode, TikTok's developer portal, and almost every Y Combinator startup that launched in the last two years. Vercel, the company that maintains Next.js, hosts a meaningful slice of the public web on the same infrastructure students will deploy to in this subtrack. That's why this stack — not Angular, not Vue, not vanilla React — is the one that pays back career time-investment fastest in 2025.
Ten lessons. The first eight take you from zero to fluent on the technical surface: project setup, App Router (layouts, pages, loading + error states), the four hooks you'll use daily, Server Components vs Client Components, API routes, Supabase for database and auth, and deploying to Vercel in under five minutes. Lesson nine is the capstone — a full-stack passion project of your choice, deployed live with a custom domain, that you'll put on your portfolio and walk through in interviews. Lesson ten is job readiness — real titles, what a competitive resume looks like, common interview questions with model answers, and the certifications that hiring managers actually recognize.
Pick the most accurate statement for 2025.