A calm, practical guide to loading, caching, and streaming data in modern React applications.

Data fetching is one of the biggest changes in the Next.js App Router era.
Instead of manually orchestrating waterfalls, suspense boundaries, and client-side fetches, Next.js encourages a server-first, cached-by-default model that results in faster and more predictable applications.

But the shift introduces new concepts:

• Where does fetch() actually run?
• When does Next.js cache responses?
• What is “revalidation”?
• How do you fetch data per segment?
• What’s the right pattern for production apps?

This chapter provides a complete, practical understanding — calm, clear, and grounded.

A calm, practical guide to understanding what runs on the server, what runs in the browser, and why this distinction matters in modern React development.

Server Components are one of the defining features of modern Next.js.
They represent a shift in how we think about rendering, data fetching, and performance.
But they also introduce new questions:

• What exactly is a Server Component?
• When do I need a Client Component?
• How do they interact?
• What patterns lead to stable, predictable apps?

In this chapter, we’ll clarify these ideas — simply, calmly, without hype.