This text discusses migrating from Role-Based Access Control (RBAC) to Fine-Grained Authorization (FGA) using WorkOS. FGA is an advanced access control model that considers several factors, such as a user's role, seniority, location, or the time of day, to decide whether a user should have access to a resource. The text provides a step-by-step guide on how to design and implement an authorization model using FGA, including defining resources, relationships, inheritance rules, and testing and validating the access model. It also mentions that in the second part of this guide, it will cover making access checks, checking for particular permissions on resources, managing FGA implementation, and favoring performance or consistency based on an application's requirements.