Global keys in Flutter are unique identifiers that can be used to access and manipulate widgets from anywhere in the widget tree[1][2][3]. They are a subclass of the Key class called GlobalKey[3].
The primary use case for global keys is to access a widget's state or context from outside its subtree[1][2]. This is useful when you need to interact with a widget from a different part of the widget tree or from outside the widget tree entirely[1].
For example, you might use a global key to access a Scaffold widget's ScaffoldState to show a SnackBar or open a drawer[1][2]. Global keys can also be used to access the state of a TextField or AnimationController from outside the widget's subtree[1].
