What is the core concept behind Vue.js?

Vue binds a JavaScript data object to an HTML element so that changing the object automatically updates the view (reactivity).

Key principles:

• HTML element becomes the "view" of an object
• Changes to the object are instantly reflected in the HTML (reactivity)
• Don't modify DOM directly - modify the data object instead

Object: { message: "Hello" }  →  View: <p>{{ message }}</p>

Vue handles the DOM updates for you.

Go deeper:

• Reactivity Fundamentals (Vue docs) — how Vue tracks which data a render used and re-renders exactly what changed.