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Data Types

Last Updated: January 3, 2026

6 min read

Understanding data types in Python is crucial because they dictate how we can manipulate our data. Think of data types as the different containers we use to store information: some are suited for numbers, others for text, and yet others for collections of items.

Mastering these types will empower you to write more efficient, effective code.

The Core Data Types

Python has several built-in data types, and understanding these is the first step in leveraging the language effectively. Let’s break them down:

  1. Numeric Types
  2. Sequence Types
  3. Mapping Types
  4. Set Types
  5. Boolean Type
  6. None Type

Each of these types serves a unique purpose and has its own characteristics that influence how we interact with data.

Numeric Types

Python includes three primary numeric types: int, float, and complex. Each serves different needs when dealing with numbers.

Integers (int)

int stands for integer, representing whole numbers without a decimal point. You can perform various arithmetic operations with integers.

Real-World Use Case

Integers are perfect for counting items, such as:

Floating Point Numbers (float)

float represents real numbers and is used for decimal points. These are crucial for calculations requiring precision, such as financial applications.

Precision Issues

Keep in mind that floating point arithmetic can lead to precision issues due to how these numbers are represented in memory.

To fix this, you can round the result:

Complex Numbers (complex)

Complex numbers have a real and imaginary part, represented as a + bj.

Practical Use Case

Complex numbers are often used in scientific calculations, such as electrical engineering and signal processing.

Sequence Types

Sequence types allow you to store collections of items. Python has three main sequence types: list, tuple, and range.

Lists

Lists are mutable, ordered collections that can contain mixed data types.

Manipulating Lists

Lists come with powerful methods for manipulation. You can sort, reverse, or even filter items:

Tuples

Tuples are similar to lists, but they are immutable. Once created, you cannot change their contents.

When to Use Tuples

Use tuples when you want to ensure that data remains unchanged, such as when returning multiple values from a function.

Range

The range type is a sequence of numbers, often used in loops.

Mapping Types

Mapping types provide a way to store key-value pairs, with the most common one being the dict.

Dictionaries (dict)

Dictionaries are mutable and unordered collections that store data in key-value pairs.

Real-World Applications

Dictionaries are perfect for situations where you need to associate values with unique keys, like user profiles or configuration settings.

Dictionary Methods

Dictionaries come with various methods for interaction:

  • .get(key): Retrieves a value.
  • .keys(): Returns all keys.
  • .values(): Returns all values.

Set Types

Sets are collections of unique items. They are mutable and unordered, meaning they cannot contain duplicate values.

Sets

Sets are great for membership testing and eliminating duplicate entries.

Use Cases

Sets are particularly useful in scenarios where you need to ensure uniqueness, like tracking user IDs or email addresses.

Set Operations

You can perform set operations like unions and intersections:

Boolean Type

The bool type represents the two truth values: True and False. These are essential in control flow, especially when making decisions.

Boolean Operations

You can perform logical operations using and, or, and not.

Real-World Applications

Booleans are often used in conditions and loops to control the flow of a program.

None Type

The None type represents the absence of a value. It is often used to signify ‘nothing’ or ‘no value here’.

Using None

You might encounter None when dealing with function returns where no value is explicitly returned.

Importance of None

Using None can help differentiate between a variable that has a value and one that hasn't been set.

Now that you understand data types, you are ready to explore numbers in more detail. In the next chapter, we will dive into int, float, and complex types, focusing on their unique properties and practical applications.