marshmallow itself is an excellent package for serialization and deserialization in Python, as well as providing validation features. It allows developers to define schemas, which can be used to represent a field in various ways (required and validation), and automatically perform validation during deserialization. We will start by implementing a data validation function in this chapter. We will implement it using the marshmallow package to ensure that the information the user entered is correct. We will work with you through various exercises and activities to test serialization and deserialization afterward with Postman.