The None Keyword

Introduction to NoneType

In Python, None represents the absence of a value or a null value. It is a special value whose data type is NoneType and is often used as a placeholder or a default value when a variable or a function parameter does not have a specific value assigned. We can assign None to any variable, but we cannot create other variables of type NoneType.

You might be wondering how None is different from 0 or an empty string (""). Let's look at a real-world scenario to understand the subtle differences. If someone sat for an exam and got a zero, their case is different from someone who did not appear for the exam, and even more distinct from someone who submitted a blank answer sheet, represented by an empty string. Suppose we are calculating the class average: A person who got a zero should be included in this calculation, but a person who did not appear for the exam (None) or submitted a blank answer ("") should be treated differently. Had we given a zero or an empty string to both students who didn’t appear, the average would not be representative of the true situation. Assigning None to the student who didn’t attend and an empty string to the one who submitted blank allows us to handle these cases appropriately. Here's an example illustrating the use of the None keyword: