Identifiers In Python|

in this article, we are going to discuss Identifiers in Python, python identifiers example, Rules for Identifiers in Python, Python Identifiers list, etc. so keep reading the article till last. Python, known for its simplicity and readability, owes much of its user-friendliness to its flexible naming system. In Python, these naming components are called identifiers. Understanding how to use identifiers properly is a fundamental step in your Python journey. This guide will take you through everything you need to know about Python identifiers, from their basic rules to best practices for writing clean and maintainable code.

Introduction to Identifiers

Identifiers, in the world of programming, are names used for various program elements such as variables, functions, classes, modules, and more. They act as labels, allowing us to refer to these elements in our code.

Rules for Naming Identifiers

Basic Rules

  1. Valid Characters: Identifiers can include letters (both uppercase and lowercase), digits, and underscores. Special characters like @, #, and $ are not allowed.
  2. Case Sensitivity: Python is case-sensitive, so myVariable and myvariable are treated as two different identifiers.
  3. Starting with Letters or Underscores: Identifiers must start with a letter (a-z, A-Z) or an underscore (_). They cannot start with a digit (0-9).
  4. Can’t Start with Numbers: While digits are allowed in identifiers, they can’t be the first character. For example, 3apples is not a valid identifier.

Reserved Words

Python has a set of reserved words (also known as keywords) that have special meanings in the language. These words cannot be used as identifiers because they are already used by Python for specific purposes. For example, words like if, else, while, and class are reserved words.

# Using a reserved word as an identifier (not allowed)
if = 42  # using reserved words will result in a syntax error
while = 44
with = 34
for = 94
as = 92
break = 99

Starting with Letters or Underscores:

Identifiers must start with a letter (a-z, A-Z) or an underscore (_). They cannot start with a digit (0-9). For example, my_variable is valid, but 123var is not.

name = "John"
_value = 42

2name = "Rohit"    #not allowed
56class3 = "mca"   #not allowed

Naming Conventions

To maintain consistency and readability in your code, Python follows certain naming conventions. These conventions are not enforced by the language but are widely adopted by the Python community.

# Snake_case
user_name = "Alice"
calculate_total_score = lambda x, y: x + y

# CamelCase
class CustomerData:
    def getUserData(self):

MAX_SIZE = 1024
PI = 3.14159


Used for variables and functions. Words are separated by underscores.

  • Usage: Variables, functions, and method names.
  • Example: user_name, calculate_total_score()


Used for class names and method names in classes. Words are capitalized without spaces.

  • Usage: Class names and method names in classes.
  • Example: MyClass, getCustomerData()


Used for constants, typically defined at the module level. Words are capitalized and separated by underscores.

  • Usage: Constants, typically defined at module level.
  • Example: MAX_SIZE, PI
user_name = "Alice"  # snake_case
calculateTotalScore = lambda x, y: x + y  # CamelCase

Best Practices

Beyond the rules and conventions, here are some best practices to keep in mind when choosing identifiers:

Choosing Descriptive Names

Choose names that convey the purpose of the variable, function, or class. For example, user_age is more descriptive than u_age.

total_score = 100
is_eligible = True

Avoiding Ambiguity

Avoid ambiguous names that might confuse other developers (or your future self). For instance, don’t use a variable named o when it could be order_amount.

o = "Order"  # Ambiguous
order_amount = 100.0  # Clear and descriptive


Maintain a consistent naming style throughout your project. If you’re using snake_case for variables, stick to it.

Examples of Identifiers

Let’s take a look at some real-world examples of Python identifiers to solidify our understanding:

  • Variable Identifier: total_cost = 1000.0
  • Function Identifier: def calculate_discount()
  • Class Identifier: class CustomerData()
  • Module Identifier: import math


Hope you must have understood, Identifiers in Python, python identifiers example, Rules for Identifiers in Python, Python Identifiers list. Identifiers breathe life into your code. They make it readable, maintainable, and understandable. As you continue your Python journey, remember the power of well-chosen names for your variables, functions, classes, and modules. They’re the labels that bring clarity and order to your code.

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