One development in the post-Sept. 11 world that aids security personnel is the Homeland Security Presidential Directive 3 (HSPD 3). As this page details, HSPD 3 established the Homeland Security Advisory System that created “a common vocabulary, context, and structure for an ongoing national discussion about the nature of the threats that confront the homeland and the appropriate measures that should be taken in response.” It’s important that all security providers understand what HSPD 3 entails, so they can respond appropriately.