Too Long; Didn't Read
Annotations are a form of metadata that provides data about a program that is not part of the program itself. Annotation can be used by the compiler to detect errors or suppress warnings. Annotations have no direct effect on the operation of the code they annotate. They can apply to packages, types (classes, interfaces, enums and annotation types), variables (class, instance and local variables — including that defined in a for or while loop), constructors, methods and parameters. The at sign character (@) indicates to the compiler that what follows is an annotated piece of code.