Parameters: Passing Data In

A function gets more useful when you can feed it data. The names inside the parentheses are parameters (the slots), and the values you pass when calling are arguments (what fills the slots).

def greet(name):
    return f"Hi {name}"

print(greet("Sam"))   # Hi Sam
print(greet("Ada"))   # Hi Ada

Here name is a parameter. When you call greet("Sam"), the argument "Sam" becomes name inside the function.

You can have several parameters, separated by commas. By default they fill in order (this is positional):

def add(a, b):
    return a + b

print(add(2, 3))   # 5  (a=2, b=3)

Order matters with positional arguments. add(2, 3) and add(3, 2) happen to match here, but greet("Hi", "Sam") would put the wrong value in each slot. Pass arguments in the same order as the parameters.