1. Indentation:

The recommendation is to use 4 spaces for indentation.

Blank Lines

In Python scripts, top-level function and classes are separated by two blank lines. 
Method definitions inside classes should be separated by one blank line.

Whitespaces

• should try to avoid whitespaces in Expressions and Statements.
• Add blank line before a single line comment
• Break up sections of code with white space.

Imports

 each import should be on a single line.

Source File Encoding

 Python 3 has UTF-8 ,the default source encoding. 

2. naming conventions

Variables naming conventions

Use snake_case And All Lower Case

snake case: when words are separated by underscores.

Example: lower_case_with_underscores.

Classes naming conventions

use CamelCase for class definitions.

CamelCase: first letter capitalized With Every word.

Example: CapitalizedWords.

3.General conventions

• Capitalize the first letter of a sentence.
• Capitalize the first letter of someone’s name.
• Add a space after the end of a sentence.
• Add a space after each word.

4. use of comments

5. line lengths

6. use of white space

Indentation

Indentation is an empty space (whitespace) used at the beginning of any statement to start new paragraph.

 indentation should be consistent throughout your code.

Indents
There are two types of indents:

Horizontal indents: spaces at the left 2 or 4 spaces.

Vertical indents(hanging indent): empty lines for splitting code into logical blocks.

Indentation in Python is mandatory.

Indentation in other languages like C,C++,Java etc is just for readability but in python, the indentation is a mandatory concept that should be followed when writing a python code, otherwise, python interpreter will  thrown IndentationError.

Reason why indentation is important in python

because the indentation serves another purpose other than code readability 

• To represent a block of code(Python treats the statements as a single block of code that  have the same indentation level.)
•  Without indentation, Python interpreter will get confused and does not know which statement to execute next or which statement belongs to which block.
• Indentation helps interpreter to understand the order in which each block/statement should be executed.

Python Indentation Rules

• The first line of Python code can’t have indentation, it will throw IndentationError.
• The best practice is to use 4 spaces for indentation.
• If you have multiple lines inside the if block, all the lines will need to be indented with same level otherwise You will get indentation error
• If there is colon at the end of a line, you will need to indent the next line/lines by ignoring your current level of indentation.
• If there is no colon, you should not indent the starting of a line.
• Python doesn't allow mixing tabs and spaces for indentation.

4-space or 2-space indentation

Indentation style

There are several styles .Pick a style that suits you, then use it consistently.

1. Allman
2. K&R(Kernighan & Ritchie Style)
3. GNU
4. Whitesmiths
5. Horstmann
6. Haskell
7. Pico
8. Ratliff
9. Lisp

K&R(Kernighan & Ritchie Style) In K&R, single-line blocks do not have braces.