You are tasked with designing a new backend architecture for a cloud-based application that handles sensitive user data. What considerations would you take into account regarding data security and compliance? How would you structure the application to enhance these factors?

## What to Cover Discuss data encryption methods, compliance standards, user authentication, and service isolation techniques. ## Strong Answer Framework Structure your response in terms of architecture layers: Client, API, Service, and Database. ## Watch Out For Neglecting to consider scalability and how compliance requirements might evolve.