This talk will briefly go over the various decorator syntaxes before breaking up the common usages of decorators into 5 categories. Effectively, these are design patterns for decorators. The usages to be considered are: A - Argument Changing Decorators -- Decorators that change a function's arguments, including changing its signature B - Binding Decorators -- Decorators that implement the Descriptor Protocol, such as the builtins: @property, @classmethod, and @staticmethod C - Control Flow Decorators -- Decorators that change when or whether the function will be called, such as @retry or @lrucache D - Descriptive Decorators -- Decorators that do not change the function, but create a reference to it elsewhere, like pytest.mark and flask.app.route E - Execution Decorators -- Decorators that retrieve source code and/or AST and alter it.