Python Keywords and Identifiers

Last Updated : 19 Aug, 2025

Python Keywords are reserved words with fixed meanings that define Python’s syntax. Cannot be used as names.
Python Identifiers are user-defined names for variables, functions, or classes. Must follow naming rules (no digits at start, only _ allowed).

Keywords in Python

Predefined and reserved words with special meanings.
Used to define the syntax and structure of Python code.
Cannot be used as identifiers, variables, or function names.
Written in lowercase, except True and False.
Python 3.11 has 35 keywords.
The keyword module provides:
- iskeyword() → checks if a string is a keyword.
- kwlist → returns the list of all keywords.

Rules for Keywords in Python

Python keywords cannot be used as identifiers.
All the keywords in Python should be in lowercase except True and False.

List of Python Keywords

Category	Keywords
Value Keywords	True, False, None
Operator Keywords	and, or, not, is, in
Control Flow Keywords	if, else, elif, for, while, break, continue, pass, try, except, finally, raise, assert
Function and Class	def, return, lambda, yield, class
Context Management	with, as
Import and Module	import, from
Scope and Namespace	global, nonlocal
Async Programming	async, await

Getting List of all Python keywords

We can also get all the keyword names using the below code.

Python

import keyword

print(keyword.kwlist)

Output

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is',...

Identifiers in Python

User-defined names for variables, functions, classes, modules, etc.
Can include letters, digits, and underscores (_).
Case-sensitive → num, Num, and NUM are different identifiers.
Python provides str.isidentifier() to check if a string is a valid identifier.

Rules for Naming Python Identifiers

It cannot be a reserved python keyword.
It should not contain white space.
It can be a combination of A-Z, a-z, 0-9, or underscore.
It should start with an alphabet character or an underscore ( _ ).
It should not contain any special character other than an underscore ( _ ).

Examples of Python Identifiers

Valid identifiers:
var1
_var1
_1_var
var_1
Invalid Identifiers
!var1
1var
1_var
var#1
var 1

Python Keywords and Identifiers Examples

Example 1: Example of and, or, not, True, False keywords.

Python

print("example of True, False, and, or, not keywords")

#  compare two operands using and operator
print(True and True)

# compare two operands using or operator
print(True or False)

# use of not operator
print(not False)

Output

example of True, False, and, or, not keywords
True
True
True

Example 2: Example of a break, continue keywords and identifier.

Python

# execute for loop
for i in range(1, 11):
    
    # print the value of i
    print(i)
    
    # check the value of i is less than 5
    # if i lessthan 5 then continue loop
    if i < 5:  
        continue
        
    # if i greater than 5 then break loop
    else:  
        break

Output

Example 3: example of for, in, if, elif, and else keywords.

Python

# run for loop
for t in range(1, 5):
  # print one of t ==1
    if t == 1:
        print('One')
   # print two if t ==2
    elif t == 2:
        print('Two')
    else:
        print('else block execute')

Output

One
Two
else block execute
else block execute

Example 4: Example of def, if, and else keywords.

Python

# define GFG() function using def keyword
def GFG():
    i=20
    # check i is odd or not 
    # using if and else keyword
    if(i % 2 == 0):
        print("given number is even")
    else:
        print("given number is odd")    
    
# call GFG() function    
GFG()

Output

given number is even

Example 5: Example of try, except, raise.

Python

def fun(num):
    try:
        r = 1.0/num
    except:
        print('Exception raises')
        return
    return r

print(fun(10))
print(fun(0))

Output

0.1
Exception raises
None

Example 6: Example of a lambda keyword.

Python

# define a anonymous using lambda keyword
# this lambda function increment the value of b
a = lambda b: b+1

# run a for loop 
for i in range(1, 6):
    print(a(i))

Output

Example 7: use of return keyword.

Python

# define a function
def fun():
  # declare a variable
    a = 5
    # return the value of a
    return a
# call fun method and store
# it's return value in a variable  
t = fun()
# print the value of t
print(t)

Output

Example 8: use of a del keyword.

Python

# create a list
l = ['a', 'b', 'c', 'd', 'e']

# print list before using del keyword
print(l)

del l[2]

# print list after using del keyword
print(l)

Output

['a', 'b', 'c', 'd', 'e']
['a', 'b', 'd', 'e']

Example 9: use of global keyword.

Python

# declare a variable
gvar = 10

# create a function
def fun1():
  # print the value of gvar
    print(gvar)

# declare fun2()
def fun2():
  # declare global value gvar
    global gvar
    gvar = 100

# call fun1()
fun1()

# call fun2()
fun2()

Output

Example 10: example of yield keyword.

Python

def Generator():
    for i in range(6):
        yield i+1

t = Generator()
for i in t:
    print(i)

Output

Example 11: Use of assert keyword.

Python

def sumOfMoney(money):
    assert len(money) != 0,"List is empty."
    return sum(money)

money = []
print("sum of money:",sumOfMoney(money))

Output:

AssertionError: List is empty.

Example 12: Use of pass keyword

Python

class GFG:
    pass
g = GFG

Example 13: Use of finally keyword

Python

def divide(a, b):
    try:
        c = a/b
        print("Inside try block")
    except:
        print("Inside Exception block")
    finally:
        print("Inside finally block")
divide(3,2)
divide(3,0)

Output

Inside try block
Inside finally block
Inside Exception block
Inside finally block

Example 14: Use of import keyword

Python

import math
print("factorial of 5 is :", math.factorial(5))

Output

factorial of 5 is : 120

Example 15: Use of is keyword

Python

x = 10
y = 20
z = x 
print(x is z)
print(x is y)

Output

True
False

Example 16: Use of from keyword

Python

from math import gcd
print("gcd of 345 and 675 is : ", gcd(345, 675))

Output

gcd of 345 and 675 is :  15

Example 17: Use of async and await keyword

Python

# code
import asyncio

async def factorial(n):
    if n == 0:
        return 1
    return n * await factorial(n - 1)

def main():
    result = asyncio.run(factorial(5))
    print(result)

if __name__ == "__main__":
    main()

Output

The async and await keywords make it easy to write asynchronous code in Python. They allow you to write code that runs concurrently with other tasks, which can improve the performance of your programs.

This program defines two functions: factorial() and main(). The factorial() function is an asynchronous function, which means it can run concurrently with other tasks. The await keyword is used to suspend the execution of the factorial() function until it completes. The main() function simply calls the factorial() function and prints the result.

Suggested Quiz

13 Questions

Can we use keywords as variables name in python?

A

No
B

Yes

Explanation:

Python keywords have predefined meanings and cannot be used as variable names.

Which of the following is the correct identifier?

A

While
B

for
C

True
D

False

Explanation:

While (with capital W) is not a Python keyword, so it can be used as an identifier. Other options are Python keywords and cannot be used as variable names.

Which of the following keywords is used to define a class in Python?

A

define
B

new
C

class
D

struct

Explanation:

The class keyword is used to define a class in Python.

Which of the following keywords is used to define a function in Python?

A

def
B

func
C

define
D

method

Explanation:

def is the keyword used to define a function in Python. After def, you specify the function name, followed by parentheses () and a colon : to start the function's body.

What keyword is used to return a value from a function in Python?

A

return
B

yield
C

output
D

send

Explanation:

The return keyword is used inside a function to send back a result or value to the caller, effectively ending the function.

Which of the following keywords is used to define an object constructor in Python?

A

init
B

constructor
C

__init__
D

define

Explanation:

__init__ is a special method in Python used to initialize an object's state when a new instance of a class is created.

Which of the following keywords is used to declare an alias for a module in Python?

A

import as
B

using
C

alias
D

import

Explanation:

The import as syntax allows you to import a module and give it a shorthand alias, which is useful for convenience.

What keyword is used to define an empty function or class in Python?

A

continue
B

skip
C

pass
D

break

Explanation:

pass is a placeholder keyword that does nothing. It is used in scenarios where we need to define a function or class but haven’t implemented it yet.

What is the maximum length of a Python identifier?

A

31 characters
B

63 characters
C

79 characters
D

Unlimited

Explanation:

Python identifiers can be of any length; there is no fixed maximum limit.

Is Python case sensitive when dealing with identifiers?

A

Yes
B

No
C

machine dependent
D

none of the mentioned

Explanation:

Python treats identifiers with different cases as distinct, so it is case-sensitive.

Which of the following is not a Python keyword?

A

else
B

finally
C

as
D

function

Explanation:

function is not a keyword in Python while the others (else, finally, as) are.

Which of the following cannot be used as an identifier in Python?

A

value
B

count1
C

_index
D

def

Explanation:

def is a reserved keyword used to define functions.

Which of these is a valid identifier in Python?

A

1value
B

val@ue
C

_value1
D

value 1

Explanation:

Identifiers can start with an underscore and contain only alphanumeric characters or underscores.

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Python Keywords and Identifiers

Keywords in Python

Rules for Keywords in Python

List of Python Keywords

Getting List of all Python keywords

Identifiers in Python

Rules for Naming Python Identifiers

Examples of Python Identifiers

Python Keywords and Identifiers Examples

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