Decorators in Python are a powerful feature that allows developers to modify or enhance the behavior of functions or methods without altering their source code. Essentially, a decorator is a function that takes another function as an argument and extends its functionality. This mechanism promotes code reusability and readability by separating the core logic of a function from its enhancements, such as logging, authentication, or timing. Decorators are commonly used in various frameworks, including Flask and Django, and can significantly streamline the development process by applying consistent behavior across multiple functions or methods.