How can you define and call a function in Python?

In Python, a function is defined using the def keyword, followed by the function name and parameters. The function is called by its name with arguments inside parentheses.

Example of defining and calling a function:

def greet(name):
    return f"Hello, {name}!"

message = greet("World")
print(message)  # Outputs: Hello, World!

Here, greet is a function that takes one parameter name and returns a greeting string. Calling greet("World") returns the string which is then printed.