Python Comments

Comments are very important while writing a program. It describes what's going on inside a program so that a person looking at the source code does not have a hard time figuring it out. You might forget the key details of the program you just wrote in a month's time. So taking time to explain these concepts in form of comments is always fruitful.
In Python, we use the hash (#) symbol to start writing a comment. It extends up to the newline character. Comments are for programmers for better understanding of a program. Python Interpreter ignores comment.

#This is a comment
#print out Hello
print('Hello')

Multi-line comments

If we have comments that extend multiple lines, one way of doing it is to use hash (#) in the beginning of each line. For example:

#This is a long comment
#and it extends
#to multiple lines

Another way of doing this is to use triple quotes, either ''' or """. These triple quotes are generally used for multi-line strings. But they can be used as multi-line comment as well. Unless they are not docstrings, they do not generate any extra code.

"""This is also a
perfect example of
multi-line comments"""

Docstring

Docstring is short for documentation string. It is a string that occurs as the first statement in a module, function, class, or method definition. We must write what a function/class does in the docstring. Triple quotes are used while writing docstrings. For example:

def double(num):
    """Function to double the value"""
    return 2*num

Docstring is available to us as the attribute __doc__ of the function.

>>> print(double.__doc__)
Function to double the value