What is a widget in Flutter?

Widgets are the central class hierarchy in the Flutter framework. A widget is an immutable description of part of a user interface . Widgets can be inflated into elements, which manage the underlying render tree. Widgets themselves have no mutable state (all their fields must be final).

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What is state of a widget?

State is information that (1) can be read synchronously when the widget is built and (2) might change during the lifetime of the widget . It is the responsibility of the widget implementer to ensure that the State is promptly notified when such state changes, using State.

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