Indentation in Python

Indentation is used to organise and group statements into blocks of code. Unlike many other programming languages, Python uses indentation instead of braces {} to define code structure.

• Statements with the same indentation belong to the same block of code.
• Indentation is created using spaces or tabs, but four spaces are commonly preferred.
• Inconsistent indentation causes an IndentationError.

print("I have no Indentation ")
    print("I have tab Indentation ")

Output

ERROR!
Traceback (most recent call last):
File "<main.py>", line 2
print("I have tab Indentation ")
IndentationError: unexpected indent

Explanation:

• First print statement has no indentation, so it is correctly executed.
• Second print statement has tab indentation, but it doesn't belong to a new block of code, that's why it throws IndentationError.

Indentation in Conditional Statements

All statements in a conditional block should have same alignment.

The code below demonstrate how we use indentation to define seperate scopes of if-else statements:

a =  20

if a >= 18:
    print('GeeksforGeeks...')
else:
    print('retype the URL.')
print('All set !')

GeeksforGeeks...
All set !

Explanation:

• Statements inside if and else are indented, which makes them part of their respective blocks.
• Since a is greater than or equal to 18, the if block executes.
• The last print() statement is outside the if-else block, so it runs every time.

Indentation in Loops

Indentation defines the set of statements that are executed repeatedly inside a loop.

j = 1
  
while(j<= 5): 
     print(j) 
     j = j + 1

1
2
3
4
5

Explanation: Both print(j) and j = j + 1 are indented, so they are part of the loop block. These statements keep executing until the condition j <= 5 becomes False.