Docstrings are used in Python to document functions, classes, and modules. A docstring is a string literal that appears as the first statement in a function, class, or module definition.

Here's an example of a function with a docstring:

def add_numbers(x, y):
    """
    Adds two numbers together.
    """
    return x + y

In this example, the docstring is enclosed in triple quotes ("""), and appears immediately after the function definition line. The docstring should provide a concise description of what the function does, including any inputs, outputs, or side effects.

You can access the docstring of a function using the __doc__ attribute:

print(add_numbers.__doc__)
# Output:
# Adds two numbers together.

Python also provides a built-in help() function that can display the docstring for a function or class:

help(add_numbers)
# Output:
# Help on function add_numbers in module __main__:
#
# add_numbers(x, y)
#     Adds two numbers together.

It's a good practice to include docstrings for all of your functions, classes, and modules, to make it easier for others (and yourself) to understand how they work and how to use them.