Annotation

Definitions

A metadata marker attached to code elements — classes, methods, fields, or parameters — that provides supplementary information to the compiler, framework, or runtime without directly altering program logic.
In plain English: A special tag you put on your code to give extra instructions to tools or frameworks, like telling a web framework which function handles a URL.
Example: "Add @Transactional to the service method and Spring will wrap it in a database transaction automatically."