It is a form of METADATA and it provides data about a PROGRAM that is not part of the program itself. An annotation has no direct effect on the operation of the code they annotate.
Uses of Annotations :
• Information for the compiler — It can be USED by the compiler to detect errors or suppress warnings.
• Compile-time and deployment-time processing — some software tools can process annotation information to generate code, XML FILES, and so forth.
• RUNTIME processing — few annotations are available to be examined at runtime.

It is a form of metadata and it provides data about a program that is not part of the program itself. An annotation has no direct effect on the operation of the code they annotate.
Uses of Annotations :
• Information for the compiler — It can be used by the compiler to detect errors or suppress warnings.
• Compile-time and deployment-time processing — some software tools can process annotation information to generate code, XML files, and so forth.
• Runtime processing — few annotations are available to be examined at runtime.