Runtime attributes (observable at runtime)
Availability: a system's capability to be available 24/7. Availability can be achieved via replication and careful design to cope with failures of hardware, software, or the network.
Security: a system's ability to cope with malicious attacks from outside or inside the system. Security can be improved by installing firewalls, establishing authentication and authorization processes, and using encryption.
Performance: increasing a system's efficiency with regard to response time, throughput, and resource utilization, attributes which usually conflict with each other.