React Native is a valuable tool for developing cross-platform mobile applications for iOS and Android, allowing developers to write a single application that functions across both platforms, with variations only at the view level. This two-part series explores building a note-taking app using React Native and GraphQL, beginning with the setup of a GraphQL server using a PostgreSQL database to serve as the app's backend. The guide walks through initializing a Node.js and Express backend server, installing necessary dependencies like Apollo Server, and defining the GraphQL schema and resolvers to manage data operations such as querying and mutations. It then details how to integrate PostgreSQL with Sequelize to enable data persistence and outlines how resolvers connect to the database through Sequelize's API, replacing the initial dummy data setup. The tutorial concludes by paving the way for the subsequent part of the series, which will focus on developing a front-end application with React Native and Apollo to consume the backend data.