if

Choosing Which Statements to Execute

The general form of an if statement is as follows:

if «condition»:
   «block»

As with function bodies, the block of statements inside an if
must be indented by four spaces.

num = int(input("Enter an integer.   "))
if num < 0:
    print("There is no square root of", num)
    print("You entered", num)

The 4 space indentation becomes a block.
The block is the group of jobs when condition is true.