The Zero Trust security framework is based on the concept of trust nothing and verify everything. It affirms that organizations must authenticate and authorize every user or device connecting to a network internally or externally before granting them access to any data or application.
This is a major shift from traditional "castle-and-moat" network security methods that focused primarily on perimeter security and by default trusted connections that passed through the perimeter to move freely throughout the network. Read more about Zero Trust here.
Source: www.webopedia.com