1. Variables

Definition

A variable is used to store a value that can be used later in the program.

Example

name = "John"
age = 20

Output

(No output)

Explanation

Variables hold data such as numbers, text, or Boolean values.

2. Variable Naming Rules (snake_case)

Rules

Use letters, numbers, and underscores (_)
Cannot start with a number
Cannot contain spaces
Cannot use special characters except _
Case-sensitive (age and Age are different)
Use snake_case for readability

Good Examples

student_name = "Alice"
total_marks = 95
is_logged_in = True

Bad Examples

2name = "Alice"
student-name = "Alice"
student name = "Alice"

Output

SyntaxError

Explanation

Use meaningful lowercase variable names separated with underscores.

3. Assign Multiple Values

Multiple Variables

x, y, z = 10, 20, 30

print(x)
print(y)
print(z)

Output

10
20
30

Explanation

Assign multiple values in a single line.

Same Value to Multiple Variables

a = b = c = 100

print(a)
print(b)
print(c)

Output

100
100
100

Explanation

All variables point to the same value.

4. Output Variables

name = "John"

print(name)

Output

John

Explanation

print() displays the value stored in a variable.

Printing Multiple Variables

name = "John"
age = 20

print(name, age)

Output

John 20

Explanation

Separate multiple values using commas.

5. Global Variables

name = "John"

def show():
    print(name)

show()

Output

John

Explanation

Global variables can be accessed inside functions.

6. Local Variables

def show():
    message = "Hello"
    print(message)

show()

Output

Hello

Explanation

Local variables exist only inside the function.

7. Python Comments

Single-line Comment

# This is a comment

print("Hello")

Output

Hello

Explanation

Python ignores comments.

Multi-line Comment

"""
This
is
a comment
"""

print("Python")

Output

Python

Explanation

Triple quotes are commonly used for multi-line comments or docstrings.

8. Indentation

if True:
    print("Correct")

Output

Correct

Explanation

Indentation defines code blocks in Python.

9. Basic Input

name = input("Enter your name: ")

print(name)

Sample Input

Alice

Output

Enter your name: Alice
Alice

Explanation

input() always returns a string.

10. Taking Integer Input

age = int(input("Enter age: "))

print(age)

Sample Input

Output

Enter age: 20
20

Explanation

Use int() to convert input into an integer.

11. Basic Output

print("Welcome")

Output

Welcome

Explanation

print() displays text or values.

12. Escape Characters

print("Hello\nPython")
print("She said \"Hi\"")

Output

Hello
Python
She said "Hi"

Explanation

Escape characters create special formatting.

Escape	Meaning
`\n`	New Line
`\t`	Tab
`\\`	Backslash
`\"`	Double Quote

13. Python Data Types

Integer

x = 25

print(type(x))

Output

<class 'int'>

Explanation

Stores whole numbers.

Float

x = 3.14

print(type(x))

Output

<class 'float'>

Explanation

Stores decimal numbers.

String

name = "Python"

print(type(name))

Output

<class 'str'>

Explanation

Stores text.

Boolean

x = True

print(type(x))

Output

<class 'bool'>

Explanation

Stores True or False.

14. Python Numbers

x = 10
y = 5.5
z = 2 + 3j

print(type(x))
print(type(y))
print(type(z))

Output

<class 'int'>
<class 'float'>
<class 'complex'>

Explanation

Python supports integers, floats, and complex numbers.

15. Type Conversion (Casting)

x = int(4.9)
y = float(5)
z = str(100)

print(x)
print(y)
print(z)

Output

4
5.0
100

Explanation

Casting converts one data type into another.

16. Strings

text = "Hello"

print(text)

Output

Hello

Explanation

Strings store characters enclosed in quotes.

String Indexing

text = "Python"

print(text[0])
print(text[-1])

Output

P
n

Explanation

Index starts from 0.

String Slicing

text = "Python"

print(text[0:3])
print(text[2:])

Output

Pyt
thon

Explanation

Slicing extracts part of a string.

Common String Methods

text = "python programming"

print(text.upper())
print(text.lower())
print(text.title())
print(text.replace("python", "Java"))
print(text.split())

Output

PYTHON PROGRAMMING
python programming
Python Programming
Java programming
['python', 'programming']

Explanation

Methods perform operations on strings.

17. Booleans

print(10 > 5)

Output

True

Explanation

Boolean values are either True or False.

18. Arithmetic Operators

Addition

print(5 + 3)

Output

Subtraction

print(10 - 4)

Output

Multiplication

print(6 * 4)

Output

Division

print(10 / 2)

Output

5.0

Floor Division

print(10 // 3)

Output

Modulus

print(10 % 3)

Output

Exponent

print(2 ** 3)

Output

19. Order of Operations

print(2 + 3 * 4)
print((2 + 3) * 4)

Output

14
20

Explanation

Parentheses have the highest priority.

20. Comparison Operators

print(5 > 3)
print(5 < 3)
print(5 == 5)
print(5 != 3)
print(5 >= 5)
print(3 <= 5)

Output

True
False
True
True
True
True

Explanation

Compare two values and return True or False.

21. Assignment Operators

x = 5

x += 2
print(x)

x *= 3
print(x)

Output

7
21

Explanation

Assignment operators modify existing values.

22. Logical Operators

print(True and False)
print(True or False)
print(not True)

Output

False
True
False

Explanation

Logical operators combine Boolean expressions.

23. Identity Operators

x = [1, 2]
y = x
z = [1, 2]

print(x is y)
print(x is z)

Output

True
False

Explanation

is checks whether two variables refer to the same object.

24. Membership Operators

numbers = [1, 2, 3]

print(2 in numbers)
print(5 not in numbers)

Output

True
True

Explanation

Check whether a value exists inside a collection.

25. Bitwise Operators

print(5 & 3)
print(5 | 3)
print(5 ^ 3)
print(~5)
print(5 << 1)
print(5 >> 1)

Output

Explanation

Bitwise operators work directly on the binary representation of integers.

26. Getting the Data Type

name = "Alice"

print(type(name))

Output

<class 'str'>

Explanation

type() returns the data type of a variable.

27. Multiple print() Arguments

name = "Alice"
age = 22

print("Name:", name)
print("Age:", age)

Output

Name: Alice
Age: 22

Explanation

print() can display multiple values separated by commas.

28. f-Strings (Formatted Strings)

name = "John"
age = 20

print(f"My name is {name} and I am {age} years old.")

Output

My name is John and I am 20 years old.

Explanation

f-Strings make it easy to insert variables into strings.

29. Keywords

import keyword

print(keyword.kwlist)

Output (Partial)

['False', 'None', 'True', 'and', 'as', 'assert', ...]

Explanation

Keywords are reserved words and cannot be used as variable names.

​1. Variables

​Definition

​Example

​Output

​Explanation

​2. Variable Naming Rules (snake_case)

​Rules

​Good Examples

​Bad Examples

​Output

​Explanation

​3. Assign Multiple Values

​Multiple Variables

​Output

​Explanation

​Same Value to Multiple Variables

​Output

​Explanation

​4. Output Variables

​Output

​Explanation

​Printing Multiple Variables

​Output

​Explanation

​5. Global Variables

​Output

​Explanation

​6. Local Variables

​Output

​Explanation

​7. Python Comments

​Single-line Comment

​Output

​Explanation

​Multi-line Comment

​Output

​Explanation

​8. Indentation

​Output

​Explanation

​9. Basic Input

​Sample Input

​Output

​Explanation

​10. Taking Integer Input

​Sample Input

​Output

​Explanation

​11. Basic Output

​Output

​Explanation

​12. Escape Characters

​Output

​Explanation

​13. Python Data Types

​Integer

​Output

​Explanation

​Float

​Output

​Explanation

​String

​Output

​Explanation

​Boolean

​Output

​Explanation

​14. Python Numbers

​Output

​Explanation

​15. Type Conversion (Casting)

​Output

​Explanation

​16. Strings

​Output

​Explanation

​String Indexing

​Output

​Explanation

​String Slicing

1. Variables

Definition

Example

Output

Explanation

2. Variable Naming Rules (snake_case)

Rules

Good Examples

Bad Examples

Output

Explanation

3. Assign Multiple Values

Multiple Variables

Output

Explanation

Same Value to Multiple Variables

Output

Explanation

4. Output Variables

Output

Explanation

Printing Multiple Variables

Output

Explanation

5. Global Variables

Output

Explanation

6. Local Variables

Output

Explanation

7. Python Comments

Single-line Comment

Output

Explanation

Multi-line Comment

Output

Explanation

8. Indentation

Output

Explanation

9. Basic Input

Sample Input

Output

Explanation

10. Taking Integer Input

Sample Input

Output

Explanation

11. Basic Output

Output

Explanation

12. Escape Characters

Output

Explanation

13. Python Data Types

Integer

Output

Explanation

Float

Output

Explanation

String

Output

Explanation

Boolean

Output

Explanation

14. Python Numbers

Output

Explanation

15. Type Conversion (Casting)

Output

Explanation

16. Strings

Output

Explanation

String Indexing

Output

Explanation

String Slicing