Summary  
This chapter explains how to define and invoke user-defined functions in code to encapsulate reusable logic, manage input parameters, and return values while isolating scope.

General domain of usage  
Modular software development and code reuse.

Master scalable data processing and analysis using PySpark, focusing on real-world e-commerce datasets. Learn to query, clean, transform, and prepare data for analytics and machine learning using Spark SQL and DataFrame APIs.

Comprehensive coverage of PySpark data processing techniques for e-commerce data, from querying to cleaning, feature engineering, and performance optimization.

User-Defined Functions (UDFs)