Introduction
Pickling is a way to store Python objects by converting them into a special format. This is useful when you want to save an object and use it again later. Pickling lets you take almost any Python object and turn it into a string of bytes. You can then save this string somewhere, like in a file.

Later on, you can load the saved string and turn it back into the original object. This process of saving objects is called serialization. In Python, we use the pickle module to do this. Unpickling is the opposite of pickling. It's how we take a pickled string and convert it back into a Python object.
What is Python Pickling?
Pickling in Python is a straightforward yet powerful way to serialize Python objects. Serialization is the process of converting an object's state to a format that can be stored or transmitted and then reconstructed later. Python provides a module called pickle that implements binary protocols for serializing and de-serializing a Python object structure.
How does Pickling work in?
When you pickle an object, Python converts the object into a byte stream that encapsulates all the information necessary to reconstruct the object in another Python script or session. This is particularly useful for saving complex data structures like lists, dictionaries, or even instances of classes.
Example: Python Object Serialization
Here's a simple example to demonstrate how you can pickle a dictionary in Python:
import pickle
# Define a dictionary to pickle
data = {'key': 'value', 'number': 42}
# Pickling the dictionary
with open('data.pkl', 'wb') as file:
pickle.dump(data, file)
print("Data has been pickled")
In this example, we first import the pickle module. Next, we create a dictionary named data with some key-value pairs. We then open a file called 'data.pkl' in write-binary mode ('wb'). Using the pickle.dump() function, we write the pickled representation of data to the file.
Why use pickling?
Pickling is used extensively in applications where program state needs to be saved and restored efficiently, or where sending data over a network is necessary. For instance, it can be used to save a trained machine learning model and load it later to make predictions without needing to retrain the model.