Quality Attributes (also called Non-Functional Requirements) are measurable properties that determine how well a system performs its intended functions. They directly influence architectural decisions.
Key Quality Attributes:

• Performance: Response time, throughput, resource utilization
• Scalability: Ability to handle increased load
• Availability: System uptime and reliability
• Security: Protection against threats and unauthorized access
• Maintainability: Ease of modification and enhancement
• Usability: User experience and interface design
• Testability: Ease of testing and validation