React
Component
A self-contained, reusable piece of UI defined as a JavaScript function that returns markup.
Reviewed by the RadarTrek editorial team · June 2026
A React component is a function that returns JSX describing a piece of the interface — a button, a card, an entire page. Components can be combined and nested to build complex UIs from small, reusable, independently testable pieces, each managing its own logic and (optionally) its own state.
Why it matters
- —Components are the fundamental unit of organisation in any React app.
- —Reusable components mean you write a button or card once and use it everywhere.
- —Thinking in components is the mental shift that makes React click for new developers.
Where to learn this
🎓
What Is React?
React Fundamentals course
This is the exact lesson that covers this term in depth — with examples, diagrams, and a hands-on exercise.