What does "@" mean in JSF?

The @ in JSF is used in so-called annotations, which serve to annotate classes, methods, and fields so that they can be handled by the compiler, development tools, and libraries. There is a more technical explanation for this, but in simple words it would be as if when you rolled the program he would check these annotations at compile time or use them for tools such as code analyzers, persistence frameworks or unit testing frameworks, among others. There are marking annotations, single-value annotations Ex. @Anotacao ("value"), complete annotations, patterns like @Override of java.lang. Ex. @Deprecated annotation is a markup that indicates that a method is deprecated and is placed in the method signature. @SuppressWarnings shuts off alerts from one part of the application code, and so on.