'Zero trust (ZT) is the term for an evolving set of cybersecurity paradigms that move defenses from static, network-based perimeters to focus on users, assets, and resources.'
This quote from NIST highlights that Zero Trust evolves based on the information, processes and tools that are available at any given time for an organization to make decisions on what work can get done. No implicit trust is granted to assets or user accounts based solely on their location, asset ownership or any other factors that organizations relied on historically. The focus is on enabling secure resources, services and workflows regardless of where those live, whenever a task is needed to be performed.