Designing a REST API involves decisions that can significantly impact aspects such as security, maintainability, and changeability, one of which is whether to use nested resources. Nested resources can enhance readability by clearly illustrating hierarchical relationships between resources, similar to directory structures in file systems, which can improve developer experience and ease debugging. However, they can also result in potentially long and complex URLs, increased redundancy, security vulnerabilities, multiple database queries, and instability if relationships change. While nested resources may sometimes be necessary due to the nature of the data source, in many cases, maintaining root resources or considering alternatives like GraphQL could be more effective in handling complex and dynamic relationships. Ultimately, the choice between using nested resources or other approaches should be informed by a careful consideration of the pros and cons, taking into account the hierarchical nature of the data, the frequency of relationship changes, and the overall development and maintenance costs.