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OSI Layer 7 Definition: Application layer.
Application layer. Layer 7 of the OSI model is the closest to end users providing network services directly to applications and interacting with software that implements a communicating component. It includes protocols like HTTP FTP SMTP and DNS that enable specific network applications and services. Security at this layer focuses on application-level threats and controls. Application layer security is addressed in standards like OWASP ASVS NIST SP 800-53 ISO 27001 and various application security frameworks. Organizations implement Layer 7 security through web application firewalls input validation authentication controls API security and application-level monitoring. For example an e-commerce platform might implement application layer security through a web application firewall that blocks attacks like SQL injection and cross-site scripting strong authentication mechanisms comprehensive input validation and real-time monitoring of application behavior for anomalies. Related terms Application security HTTP/HTTPS API security Web application firewall Input validation Authentication OWASP Top 10 Application protocols.