Zero-trust security is a conceptual framework and operational methodology for designing and implementing information security systems that fundamentally reject the traditional perimeter-based security model, assuming no implicit trust in any user, device, or network segment regardless of location. As an academic concept and research area, it investigates rigorous mechanisms for identity and context verification, dynamic policy enforcement, microsegmentation, least privilege access, and continuous security monitoring of all access attempts and data flows. Its significance lies in addressing the complexities of modern, distributed computing environments by mitigating risks associated with insider threats, lateral movement, and the dissolution of traditional network perimeters.