A function that always does exactly the same thing is limited. Parameters let you hand it information each time you call it:

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

greet("Ada")
greet("Grace")

name in the def line is a parameter: a variable that only exists inside the function. When you call greet("Ada"), the value "Ada", called the argument, is stored in name before the block runs.

A function can take several parameters, separated by commas. Arguments are matched to parameters in order:

def describe(animal, sound):
    print(f"The {animal} says {sound}.")

describe("cow", "moo")
describe("duck", "quack")
describe("quack", "duck")

The last call shows why order matters.