.format(first_name)

In general, similar things will happen, but using .format causes something special to happen. If you say:

print("Hello {}!".format(first_name))

The call to format will cause it to create a new string, which has been formatted in the way you requested. While you could just do:

print("Hello", firstname + "!")

And it will do the same thing, it is not as flexible. The second method is handing a list to the call to print, and it will print each thing in order, with a space between each one.

By using .format, we can do more complex things, with more control over what happens. For a silly example, print(a,b) will always put a space between a and b. But by using format, we can control if the space is there. And it you look into the manual, you'll see you can do more complicated things as well.

also, (please correct me if im wrong) wouldnt

print(first_name + "!")

also make all future first name calls have the "!"? (just started today so please forgive the n00b post)

Just calling:

print(first_name + "!")

Will not change the value of first_name. If you wanted to update the value of first_name, you would have to do something like:

first_name = first_name + "!"

But if you just do the print, you are not actually setting a new value for first_name.

you can use as well print(f"Have a great day {first_name}!"}