Python Decorators Explained: From Basics to Advanced Patterns 2026

Python decorators are one of the most powerful features in the language. Once you understand them, you'll use them everywhere. Here's everything you need to know. What is a Decorator? A decorator is a function that takes another function and extends its behavior without modifying it. It's syntactic sugar for wrapping functions. def my_decorator ( func ): def wrapper ( * args , ** kwargs ): print ( " Before " ) result = func ( * args , ** kwargs ) print ( " After " ) return result return wrapper @my_decorator def greet ( name ): print ( f " Hello, { name } ! " ) greet ( " Alice " ) # Before # Hello, Alice! # After This is equivalent to greet = my_decorator(greet) . Preserving Function Metadata Without functools.wraps , decorated functions lose their identity: import functools def my_decorator ( func ): @functools.wraps ( func ) # Preserves __name__, __doc__, etc. def wrapper ( * args , ** kwargs ): return func ( * args , ** kwargs ) return wrapper @my_decorator def greet ( name ): """ G