Zero Trust security is an IT security model that requires strict identity verification for every person and device trying to access resources on a private network, regardless of whether they are sitting within or outside of the network perimeter.
Traditional IT network security trusts anything inside the network ('castle and moat' concept) - Zero Trust architecture trusts nothing.
Some of the main principles of Zero Trust Security include:
https://www.cloudflare.com/en-au/learning/security/glossary/what-is-zero-trust/