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identifiers in python

An In-depth Guide to Python Identifiers

Python, a popular high-level programming language, is simple, readable, and has a large library. When programming in Python, it is essential to understand the concept of keywords and identifiers. These two concepts are the building blocks of any programming language and play a vital role in writing error-free Python code. In this article, we will discuss keywords and Identifiers in Python, their importance, and their differences.

Keywords in Python (Reserved Words)

Python keywords are special words that cannot be variable names. Python reserves 35 keywords. Language-specific words are unchangeable.

List of Keywords in Python:

Below is the list of Python’s 35 keywords:

and as assert break class continue def del elif else except False finally for from global if import in is lambda None nonlocal not or pass raise return try True while with yield

Let’s discuss some of these keywords in more detail:

  • and or: These are logical operators used for combining conditions.
  • if, Elif, and else: These are conditional statements used for executing a block of code based on a specific condition.
  • for and while These are loop statements used for iterating over a sequence of elements.
  • def: This is a keyword used for defining a function in Python.
  • class: This is a keyword used for defining a class in Python.
  • try, except, and finally: These are used for error handling and exception handling.
  • import: This is a keyword used for importing modules or packages into a Python program.

Python variables and identifiers cannot use these keywords.

Identifiers in Python

Identifiers in Python name variables, functions, classes, and other objects. Code references these objects using them. An identifier can be any combination of letters, digits, and underscores, but it cannot start with a digit.

Rules for Naming Identifiers in Python

Python identifiers must follow rules. These rules are as follows:

  1. The first characters must be letters or underscores.
  2. Use letters, numbers, and underscores.
  3. The name is case-sensitive.
  4. Identifiers cannot be a keyword.

Let’s take a closer look at each of these rules.

The first characters must be letters or underscores:

  1. The first character of an identifier in Python must be a letter or an underscore. It cannot start with a digit. For example, “myVar” and “_myVar” are valid identifiers in python, but “1Var” is not a valid identifier.

Use letters, numbers, and underscores.

  1. Letters, numbers, and underscores can follow the initial character in an identification.

The name is case-sensitive:

  1. Python is case-sensitive, thus uppercase and lowercase letters are different. For example, “myVar” and “myvar” are two different identifiers.

Identifiers cannot be a keyword:

  1. identifiers in python cannot be the same as a keyword in Python. Keywords cannot be variable or identifier names since the language reserves them. Python keywords “if” and “while” cannot be identifiers.

Difference Between Keywords and Identifiers in Python

Python keywords and identifiers specify names, although they differ:

  1. Python keywords are not identifiers. Variables, functions, and classes have user-defined identifiers.
  2. The number of words: Keywords are single words that have a special meaning in Python. identifiers in python can contain letters, numbers, and underscores.
  3. Lowercase keywords: Capitalization changes the meaning of case-sensitive identifiers.
  4. Keywords cannot be variable names. Identifiers are useful beyond naming regulations.

Different Types of Identifiers in Python

In Python, there are three types of identifiers in python: variable names, function names, and class names.

  1. Name-storing variables The program can change variables. Variable names can include letters, numerals, and underscores, but they must obey naming restrictions. They cannot start with a number and cannot be a keyword.



x = 5 y = “hello”

  1. Function names: These are used to define functions. A function is a coded task. To define a function, we use the def keyword followed by the function name and a set of parentheses. The function name should follow the same rules as variable names.



def my_function(): print(“Hello World!”)

  1. Definitions: Class names. A class is a blueprint for creating objects that have common properties and methods. The class keyword and class name define a class. The class name should follow the same rules as variable names.



class MyClass: def __init__(self, name): = name def greet(self): print(“Hello, ” +


In summary, keywords and Identifiers in Python are fundamental concepts in Python programming. Language meaning prevents keywords from being identifiers. Yet, user-chosen IDs represent variables, functions, and classes. Identifiers must start with letters or underscores and cannot be keywords. Understanding the differences between keywords and identifiers is important for writing effective and error-free Python code.

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