Why are Flutter widgets called lightweight components?

Widgets in Flutter describe only the current configuration of a UI element, not the element instance itself. When the state changes, widgets are rebuilt, creating a new instance, but the Dart VM efficiently compares the old and new widgets, updating only the parts of the render tree that have actually changed. This allows avoiding costly operations of creating and deleting native UI elements, making them "lightweight".

• Immutability: Widgets are immutable, which simplifies their comparison and reuse.
• Declarative approach: Describing UI as widgets is declarative, providing high performance during changes.
• Efficient Diffing algorithm: Flutter uses an optimized widget comparison algorithm for quick UI updates.

Example of creating a simple text widget:

// Creating a widget object
Text(
  'Hello, world!', // Widget configuration
  style: TextStyle(fontSize: 20.0),
);

When the text changes, a new Text object with a new configuration will be created, but rendering will be updated efficiently.