The main purpose of keys are to maintain a widget’s state even if it’s moved or duplicated inside the widget tree.

It’s a core topic to understand as a Flutter developer because there are several situations in which keys are necessary to maintain the robustness of the application.

Not using keys at all can lead to undesired behavior that shows subtly during the usage of your apps. In order to prevent these unwanted UX glitches, it’s good to know the meaning of keys.

To sum it up, in Flutter, a key is a unique identifier for a widget. It aids the framework in tracking widgets in the widget tree.