Keys in Flutter are unique identifiers used to track and maintain the state of widgets as they move around or are modified in the widget tree[1][2][3]. They help the framework efficiently update the user interface by identifying which widgets have changed between renders.
You should use keys in the following situations[1][2][3]:
When modifying a collection of widgets of the same type that hold state, such as adding, removing, or reordering items in a ListView
To preserve the state of a widget when it moves to a different location in the widget tree
To maintain the scroll position of a ListView when the list contents change
To enable animations when adding, removing or reordering widgets
There are several types of keys to choose from[1][2][4]:
ValueKey - uses a simple value like a string or integer to identify the widget
ObjectKey - uses a unique object to identify the widget, useful for...
