This tutorial guides developers through creating a messaging application using GraphQL and React. The tutorial is divided into eight parts, each focusing on a specific aspect of the application. In this part, we focus on input types and custom resolvers, which allow us to define the structure of our data and query it in a flexible way. We learn how to use field arguments, make the most out of Apollo's normalized cache, and create a GraphQL input type to keep client mutation signatures tidy. The tutorial also covers reading the channel name from the cache using a custom resolver, which enables us to display the channel name immediately while loading the messages in the background. By following this tutorial, developers can build a fully functional messaging application with real-time updates and pagination.