Zero-trust
A security model where no trust is granted based on network position — everything is verified on every request.
Old model: firewall at the edge, "inside" is safe. Problem: when an attacker gets in (via phishing, a zero-day in a service) they have free reign. Zero-trust says: even the inside has to be authenticated on every access.
In practice: service-to-service mTLS, short-lived tokens, identity-based access rather than IP-based. Driven by Google's BeyondCorp as inspiration.