Security Architecture Design, multiple layers, defense in depth, network layer, firewall, IDS, IPS, VPN, encryption, access control, authentication, authorization, accounting, auditing, application layer, secure coding practices, secure data storage, secure communication protocols, presentation layer, user interface, input validation, error handling, business logic layer, data processing, workflow management, database layer, data encryption, backup and recovery, infrastructure layer, network segmentation, server hardening, physical security, surveillance cameras, motion detectors, perimeter fencing, data center, cloud security, hybrid security model, zero-trust architecture, micro-segmentation, DevSecOps practices, threat modeling, risk assessment, compliance and governance, incident response, disaster recovery, security monitoring, log analysis, SIEM integration.