This document discusses custom machine learning recipes in H2O Driverless AI. It introduces bring your own recipes (BYOR), which allows users to write their own Python code snippets called recipes to customize Driverless AI's machine learning workflow. The document provides an overview of writing recipes, including how to build transformers, scorers, and models. It also covers testing and debugging recipes and more advanced options like importing packages and setting recipe parameters. The goal of BYOR is to give users flexibility and control over Driverless AI's automation to best solve their specific machine learning problems.