Lesson 11 of 70 – Python Data Types

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Python Data Types

In Python, a data type tells us what kind of value a variable contains. Python has several built-in data types such as numbers, strings, lists, tuples, sets, dictionaries and Boolean values.

Note: Python is dynamically typed, so you do not need to specify the data type when creating a variable. Python determines it automatically from the assigned value.

What is a Data Type?

A data type defines the kind of data stored in a variable. For example:

name = "Rahul"
age = 20
price = 99.50
is_student = True

Here, each variable contains a different type of data.

Python Built-in Data Types

Python provides several built-in data types. The commonly used types are:

str – String
int – Integer
float – Floating-point number
complex – Complex number
bool – Boolean
list – List
tuple – Tuple
set – Set
dict – Dictionary
NoneType – None value

String Data Type

The str data type is used to store text. Strings can be written using single or double quotation marks.

name = "Rahul"
city = 'Patna'

print(name)
print(city)

Output:
Rahul
Patna

Integer Data Type

The int data type is used to store whole numbers without decimal points.

age = 25
marks = 90
number = -10

print(age)
print(marks)
print(number)

Output:
25
90
-10

Float Data Type

The float data type is used to store numbers containing decimal values.

price = 99.50
height = 5.8
temperature = -2.5

print(price)
print(height)
print(temperature)

Output:
99.5
5.8
-2.5

Complex Data Type

The complex data type is used to represent complex numbers. A complex number contains a real part and an imaginary part.

number = 3 + 4j

print(number)

Output:
(3+4j)

In Python, j represents the imaginary part of a complex number.

Boolean Data Type

The bool data type represents one of two values: True or False.

is_student = True
is_teacher = False

print(is_student)
print(is_teacher)

Output:
True
False

List Data Type

A list is used to store multiple values in a single variable. Lists are written using square brackets [ ].

fruits = ["Apple", "Banana", "Mango"]

print(fruits)

Output:
['Apple', 'Banana', 'Mango']

Lists can contain different types of values.

data = ["Rahul", 20, 85.5, True]

print(data)

Tuple Data Type

A tuple is similar to a list, but tuples are immutable. Tuples are usually written using parentheses ( ).

colors = ("Red", "Green", "Blue")

print(colors)

Output:
('Red', 'Green', 'Blue')

Set Data Type

A set is an unordered collection of unique values. Sets are written using curly brackets { }.

numbers = {10, 20, 30, 40}

print(numbers)

A set automatically removes duplicate values.

numbers = {10, 20, 20, 30}

print(numbers)

Output:
{10, 20, 30}

Dictionary Data Type

A dictionary stores data in key-value pairs. Dictionaries are written using curly brackets.

student = {
    "name": "Rahul",
    "age": 20,
    "marks": 85
}

print(student)

Output:
{'name': 'Rahul', 'age': 20, 'marks': 85}

NoneType

The None value represents the absence of a value. Its data type is called NoneType.

result = None

print(result)
print(type(result))

Output:
None
<class 'NoneType'>

Checking Data Type with type()

The type() function is used to determine the data type of a value or variable.

name = "Rahul"
age = 20
price = 99.50

print(type(name))
print(type(age))
print(type(price))

Output:
<class 'str'>
<class 'int'>
<class 'float'>

Checking Multiple Data Types

name = "Amit"
age = 21
height = 5.7
student = True
marks = [80, 85, 90]

print(type(name))
print(type(age))
print(type(height))
print(type(student))
print(type(marks))

Output:
<class 'str'>
<class 'int'>
<class 'float'>
<class 'bool'>
<class 'list'>

Changing Data Types

A variable can be assigned a value of a different data type later.

x = 10

print(type(x))

x = "Hello"

print(type(x))

Output:
<class 'int'>
<class 'str'>

This is possible because Python uses dynamic typing.

Sequence Data Types

Some Python data types are used to store collections of values. Common sequence types include:

String – str
List – list
Tuple – tuple

name = "Python"

numbers = [10, 20, 30]

values = (1, 2, 3)

Mutable and Immutable Data

Python data types can also be understood as mutable or immutable.

Mutable objects can be changed after they are created. For example, lists are mutable.

numbers = [10, 20, 30]

numbers[0] = 100

print(numbers)

Output:
[100, 20, 30]

Tuples and strings, on the other hand, are immutable.

Data Type Example

name = "Rahul"
age = 22
salary = 25000.50
is_employee = True
skills = ["Python", "SQL", "HTML"]
address = ("Patna", "Bihar")

print("Name:", name)
print("Age:", age)
print("Salary:", salary)
print("Employee:", is_employee)
print("Skills:", skills)
print("Address:", address)

Output:
Name: Rahul
Age: 22
Salary: 25000.5
Employee: True
Skills: ['Python', 'SQL', 'HTML']
Address: ('Patna', 'Bihar')

Key Points

Data types define the kind of value stored in Python.
str is used for text.
int is used for whole numbers.
float is used for decimal numbers.
complex is used for complex numbers.
bool stores True or False.
list stores a collection of values.
tuple stores an immutable collection.
set stores unique values.
dict stores key-value pairs.
NoneType represents None.
The type() function is used to check the data type.

🧠 Quick Quiz

Question: Which data type is used to store a whole number in Python?

int
str
float
list

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Python Data Types

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