Python Basics for Beginners

01. Introduction to Python

Python is a popular programming language used in web development, automation, data analysis, artificial intelligence, and cybersecurity.

Python is beginner-friendly because its syntax is easy to read and understand.

Your First Python Program

The print() function displays information on the screen.

print("Hello, World!")

Hello, World!

Python Comments

Comments help programmers explain their code. Python ignores comments while executing a program. A single-line comment starts with #.

# This is a comment
print("Learning Python")

Learning Python

Python Indentation

Indentation means adding spaces at the beginning of a line. Python uses indentation to group statements inside blocks such as if statements and loops.

if 5 > 2:
    print("Five is greater")

Five is greater

print("My name is Alex")

My name is Alex

print("Hello")
print("Welcome to Python")

Hello
Welcome to Python

02. Python Variables

A variable is a name that refers to a value. Variables allow us to store and use information inside a program.

Python does not require us to declare a variable's data type before assigning a value.

Example

name = "John"
age = 20

print(name)
print(age)

John
20

Changing Variable Values

A variable can be assigned a new value. The latest assigned value replaces its previous value.

age = 20
age = 25

print(age)

25

Variable Naming Rules

• Names can contain letters, numbers, and underscores.
• Names cannot start with a number.
• Names are case-sensitive.
• Python keywords cannot be used as variable names.

name = "Alex"
age = 21
city = "Delhi"

print(name)
print(age)
print(city)

Alex
21
Delhi

number = 10
number = 50

print(number)

50

03. Python Data Types

A data type tells us what kind of value a variable contains. Python supports different types of data, including numbers, text, collections, and Boolean values.

Common Python Data Types

Using type()

The type() function tells us the data type of a value.

name = "Alex"
age = 20
percentage = 95.8
is_student = True

print(type(name))
print(type(age))
print(type(percentage))
print(type(is_student))

<class 'str'>
<class 'int'>
<class 'float'>
<class 'bool'>

List, Tuple, Set, and Dictionary

fruits = ["apple", "banana"]
numbers = (10, 20)
unique = {1, 2, 3}
student = {"name": "Alex", "age": 20}

print(fruits)
print(numbers)
print(sorted(unique))
print(student)

['apple', 'banana']
(10, 20)
[1, 2, 3]
{'name': 'Alex', 'age': 20}

a = 10
b = 5.5
c = "Python"

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

<class 'int'>
<class 'float'>
<class 'str'>

fruits = ["apple", "mango", "banana"]
print(fruits)

['apple', 'mango', 'banana']

04. Type Conversion in Python

Type conversion means changing a value from one data type to another.

For example, we can convert a string containing digits into an integer using int().

Example

number = "123"

print(type(number))

number = int(number)

print(type(number))
print(number + 10)

<class 'str'>
<class 'int'>
133

Common Conversion Functions

• int() converts a suitable value to an integer.
• float() converts a suitable value to a floating-point number.
• str() converts a value to a string.

number = "50"
number = int(number)

print(number + 25)

75

number = 12
text = str(number)

print(type(text))

<class 'str'>

05. Input and Output in Python

The input() function accepts information entered by the user.

The print() function displays information on the screen.

Taking User Input

name = input("Enter your name: ")

print("Hello", name)

Enter your name: Alex
Hello Alex

Taking Number Input

The input() function returns a string. We use int() when we need to convert valid whole-number input into an integer.

num1 = int(input("First number: "))
num2 = int(input("Second number: "))

print("Sum:", num1 + num2)

First number: 10
Second number: 20
Sum: 30

Using sep in print()

The sep parameter controls the separator between values displayed by print().

print(1, 2, 3, sep="-")

1-2-3

name = input("Enter name: ")
print("Welcome", name)

Enter name: Alex
Welcome Alex

a = int(input("First: "))
b = int(input("Second: "))

print("Result:", a * b)

First: 5
Second: 4
Result: 20

06. Arithmetic Operators

Arithmetic operators perform mathematical calculations such as addition, subtraction, multiplication, and division.

Example

a = 10
b = 3

print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a // b)
print(a % b)
print(a ** b)

13
7
30
3.3333333333333335
3
1
1000

print(25 % 4)

1

print(5 ** 3)

125

07. Assignment and Comparison Operators

Assignment Operators

Assignment operators assign or update values stored in variables.

number = 10
number += 5

print(number)

number *= 2

print(number)

15
30

number += 5 means number = number + 5.

Comparison Operators

Comparison operators compare values and return True or False.

a = 10
b = 20

print(a == b)
print(a != b)
print(a < b)

False
True
True

number = 20
number -= 5

print(number)

15

print(50 > 30)

True

08. Logical, Identity, and Membership Operators

Logical Operators

Logical operators combine or reverse conditions.

• and returns True when both Boolean conditions are True.
• or returns True when at least one Boolean condition is True.
• not reverses a Boolean result.

a = True
b = False

print(a and b)
print(a or b)
print(not a)

False
True
False

Identity Operators

Identity operators check whether two variables refer to the same object.

a = [1, 2]
b = a
c = [1, 2]

print(a is b)
print(a is c)
print(a == c)

True
False
True

Here, a and b refer to the same list. The list stored in c has equal contents, but it is a different object.

Membership Operators

Membership operators check whether a value is present in a collection.

fruits = ["apple", "banana", "mango"]

print("banana" in fruits)
print("grape" not in fruits)

True
True

number = 10

print(number > 5 and number < 20)

True

languages = ["Python", "Java", "C"]

print("Python" in languages)

True

09. Bitwise Operators and Binary Numbers

Computers represent information using binary digits called bits. A bit can have the value 0 or 1.

Binary to Decimal

Binary uses base 2, while decimal uses base 10.

For example, binary 10110 equals decimal 22.

number = 0b10110

print(number)
print(bin(22))

22
0b10110

Bitwise Operators

Bitwise operators work on the binary representation of integers.

Example

a = 5
b = 3

print(a & b)
print(a | b)
print(a ^ b)
print(~a)
print(a << 1)
print(a >> 1)

1
7
6
-6
10
2

print(bin(10))

0b1010

print(7 << 1)

14

10. Beginner Python Projects

Now use the concepts you have learned to create small Python programs.

Project 1 — Sum of Two Numbers

This program asks the user for two numbers and displays their sum.

num1 = int(input("First number: "))
num2 = int(input("Second number: "))

result = num1 + num2

print("Sum:", result)

First number: 10
Second number: 20
Sum: 30

Project 2 — Volume of a Sphere

The volume of a sphere is calculated using:

Volume = (4 / 3) × π × radius³

import math

radius = float(input("Enter radius: "))

volume = (4 / 3) * math.pi * radius ** 3

print("Volume:", round(volume, 2))

Enter radius: 3
Volume: 113.1

Project 3 — Celsius to Fahrenheit

This program converts a temperature from Celsius to Fahrenheit.

Fahrenheit = (Celsius × 9 / 5) + 32

celsius = float(input("Enter Celsius: "))

fahrenheit = (celsius * 9 / 5) + 32

print("Fahrenheit:", fahrenheit)

Enter Celsius: 25
Fahrenheit: 77.0

length = float(input("Length: "))
width = float(input("Width: "))

area = length * width

print("Area:", area)

Length: 10
Width: 5
Area: 50.0

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

if number % 2 == 0:
    print("Even")
else:
    print("Odd")

Enter number: 7
Odd

km = float(input("Kilometers: "))

meters = km * 1000

print("Meters:", meters)

Kilometers: 2
Meters: 2000.0

Additional Python Learning Resources

You can learn more and practice Python using these resources.

• Official Python Tutorial
• Python Getting Started Guide
• HackerRank Python Practice