In Dart, metadata provides additional information about the code. It begins with the character @ followed by either a reference to a compile-time constant or a call to a constant constructor.

There are four commonly used annotations in Dart:

@Deprecated: This is used to indicate that a feature/method/class is deprecated and should not be used because it will be removed in future versions. @deprecated: This is similar to @Deprecated, with the difference being that a message can be passed with @Deprecated. @override: This is used to indicate that a method is intended to override a method from a superclass. @pragma: This is used to provide additional information to the Dart compiler.