refers to the structure and the rules.
1 + 2)
does not appear until after
the program has started (also called exceptions).
second = "World"
first + " " + secoend
will not generate errors but it will not do the right thing.
num1 = input('Enter number 1: ')
num2 = input('Enter number 2: ')
sum = num1 + num2
sum = int(num1) + int(num2)
... 3 lines