React.js (React) is a JavaScript library for building 🔥 interactive and dynamic user interfaces (UIs)—especially for single-page applications (SPAs).

🎯 Why React?

✅ Fast & Efficient – Uses a Virtual DOM to update only what’s needed.

✅ Component-Based – Breaks UI into reusable pieces like LEGO 🧱.

✅ Declarative UI – Just tell React how things should look, and it takes care of updates.

✅ Huge Ecosystem – Works with React Router (for navigation) & Redux/Context API (for state management).

🌍 Where is React Used?

💙 Facebook & Instagram – React was created by Facebook!

🎬 Netflix – For a seamless watching experience 🍿.

🛍 E-commerce – Amazon, Shopify & more!

📊 Dashboards & Admin Panels – Interactive data visualization 📈.