Keywords are the reserved words in Python.
We cannot use a keyword as a variable name, function name or any other identifier. They are used to define the syntax and structure of the Python language.
In Python, keywords are case sensitive.
There are 33 keywords in Python 3.7. This number can vary slightly over the course of time.
All the keywords except
None are in lowercase and they must be written as they are. The list of all the keywords is given below.
An identifier is a name given to entities like class, functions, variables, etc. It helps to differentiate one entity from another.
Rules for writing identifiers
- Identifiers can be a combination of letters in lowercase (a to z) or uppercase (A to Z) or digits (0 to 9) or an underscore
_. Names like
print_this_to_screen, all are a valid examples.
- An identifier cannot start with a digit.
1variableis invalid, but
variable1is a valid name.
- Keywords cannot be used as identifiers.
- We cannot use special symbols like ! @, #, $, %, etc. in our identifier.
- An identifier can be of any length.
Things to Remember
Python is a case-sensitive language. This means,
variable are not the same.
Always give the identifiers a name that makes sense. While
c = 10 is a valid name, writing
count = 10 would make more sense, and it would be easier to figure out what it represents when you look at your code after a long gap.
Multiple words can be separated using an underscore, like