Python Indentation

Most of the programming languages like C, C++, and Java use braces { } to define a block of code. Python, however, uses indentation.

A code block (body of a function, loop, etc.) starts with indentation and ends with the first unindented line. The amount of indentation is up to you, but it must be consistent throughout that block.

Generally, four whitespaces are used for indentation and are preferred over tabs. Here is an example.

for i in range(1,11):
    print(i)
    if i == 5:
        break

The enforcement of indentation in Python makes the code look neat and clean. This results in Python programs that look similar and consistent.

Indentation can be ignored in line continuation, but it's always a good idea to indent. It makes the code more readable. For example:
if True:
    print('Hello')
    a = 5

and
if True: print('Hello'); a = 5

both are valid and do the same thing, but the former style is clearer.