Data Types In Python

5th February 2026 by Tanishq Chavan

Python C C++ Javascript React JS

Python Data Types and Constants: A Comprehensive Guide

In programming, data type is an important concept. Variables can store data of different types, and different types can do different things.

1. Built-in Data Types

Python has the following data types built-in by default, in these categories:

2. Getting the Data Type

You can get the data type of any object by using the type() function:

x = 5
print(type(x)) # Output: <class 'int'>

3. Numeric Types

Python has three distinct numeric types: int, float, and complex.

x = 1    # int
y = 2.8  # float
z = 1j   # complex

[!NOTE] Floats can also be scientific numbers with an "e" to indicate the power of 10. x = 35e3

4. Sequence Types: List, Tuple, and Range

List

Lists are used to store multiple items in a single variable. They are ordered and changeable.

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

Tuple

Tuples are used to store multiple items in a single variable. They are ordered and unchangeable.

coordinates = (10.0, 20.0)

Range

The range() function returns a sequence of numbers, starting from 0 by default.

x = range(6)

5. Mapping Type: Dictionary

Dictionaries are used to store data values in key:value pairs. They are ordered (as of Python 3.7) and changeable.

car = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}

6. Boolean Type

Booleans represent one of two values: True or False.

print(10 > 9) # Output: True
is_active = True

7. Type Casting

If you want to specify the data type of a variable, this can be done with casting.

x = str(3)    # x will be '3'
y = int(3)    # y will be 3
z = float(3)  # z will be 3.0

Python Constants: Best Practices

A constant is a type of variable whose value cannot be changed. It is helpful to think of constants as containers that hold information which cannot be altered later.

1. How to Define Constants

In Python, constants are usually declared and assigned in a module (a separate file).

[!IMPORTANT] Technical Note: Python does not actually have built-in "true" constants that are protected from being changed. Instead, we use a naming convention to tell other developers that a variable should be treated as a constant.

2. Naming Convention

Constants are usually written in all CAPITAL LETTERS with underscores separating words.

PI = 3.14
GRAVITY = 9.8
MAX_USERS = 100
API_KEY = "your_secret_key"

3. Using a Separate File

The best practice is to create a file named constants.py and store all your constants there.

constants.py

# constants.py
PI = 3.14
GRAVITY = 9.8

Step 2: Import in your main code

import constants

print(constants.PI)
print(constants.GRAVITY)

4. Rules for Constants

Meaningful Names: Use names that describe the value (e.g., WIDTH instead of W).
Never Reassign: Once a constant is defined, do not change its value in the code.
Global Scope: Constants are typically defined at the top of a file or in a dedicated module.

5. Literal Constants

Literals are the actual values assigned to variables or constants.