What Data Type Is a Dictionary?


Heather Bennett

HTML Tutorial: What Data Type Is a Dictionary?

In Python, a dictionary is a powerful data type that allows you to store and retrieve data using key-value pairs. It is similar to a real-life dictionary where you can look up a word and find its corresponding definition. In this tutorial, we will explore the characteristics of the dictionary data type and how it can be used in programming.

Defining a Dictionary

To create a dictionary in Python, you can use curly braces ({}) or the built-in dict() function. The keys and values are separated by colons (:), and each key-value pair is separated by commas (,). Let’s look at an example:

my_dict = {'name': 'John', 'age': 25, 'country': 'USA'}

Here, we have created a dictionary called my_dict with three key-value pairs. The keys are ‘name’, ‘age’, and ‘country’, and their corresponding values are ‘John’, 25, and ‘USA’.

Accessing Dictionary Values

You can access the values of a dictionary by referencing their respective keys. To do this, you simply need to provide the key within square brackets ([]). Let’s see an example:


This will output:


In this case, we accessed the value associated with the key ‘name’ in the my_dict dictionary.

Modifying Dictionary Values

One of the key features of dictionaries is that they are mutable, meaning you can modify their values. To change the value associated with a particular key, you can simply assign a new value to it. Let’s see an example:

my_dict['age'] = 26

After executing this code, the value associated with the ‘age’ key in my_dict will be updated to 26.

Dictionary Methods

The dictionary data type comes with several useful methods that allow you to perform various operations on dictionaries. Some commonly used methods include:

  • .keys(): Returns a list of all keys in the dictionary.
  • .values(): Returns a list of all values in the dictionary.items(): Returns a list of all key-value pairs in the dictionary as tuples.get(key): Returns the value associated with a specified key. If the key does not exist, it returns None or a default value.pop(key): Removes and returns the value associated with a specified key from the dictionary.

You can utilize these methods to manipulate and extract data from dictionaries efficiently.

Nested Dictionaries

In Python, you can have dictionaries nested within other dictionaries. This allows you to organize and represent complex data structures. Let’s consider an example:

person = {
  'name': 'John',
  'age': 25,
  'address': {
    'street': '123 Main St',
    'city': 'New York',
    'country': 'USA'

In this case, we have a person dictionary that contains another dictionary called address. The nested dictionary stores information about the person’s address.

To access values from the nested dictionary, you can use multiple square brackets. For example:


This will output:

‘New York’

Here, we accessed the value associated with the key ‘city’ from the nested dictionary within the person dictionary.


In this tutorial, we explored the dictionary data type in Python. We learned how to define dictionaries, access and modify their values, and utilize various methods for efficient data manipulation.

Additionally, we discovered how dictionaries can be nested within each other to represent complex data structures. With its versatility and flexibility, the dictionary data type is an essential tool in Python programming.

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