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Keywords and Identifiers

Python Keywords and Identifiers

In this tutorial, you will learn about keywords (reserved words in Python) and identifiers (names given to variables, functions, etc.).

Python Keywords

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 True, False and None are in lowercase and they must be written as they are. The list of all the keywords is given below.

Python Identifiers

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

  1. 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 myClass, var_1 and print_this_to_screen, all are valid example.
  2. An identifier cannot start with a digit. 1variable is invalid, but variable1 is a valid name.
  3. Keywords cannot be used as identifiers.