Tizen is an open source operating system for mobile and embedded devices. The document discusses security features in Tizen including access control using SMACK labeling, application isolation through privileges and features, and the Content Security Framework for security checks. While Tizen uses SMACK and a two-stage access control model to sandbox web applications, the document notes room for improvement in areas like ASLR and DEP for native applications to prevent vulnerabilities like buffer overflows.