TrustZone is a hardware security architecture used in some CPUs and microcontrollers to split execution into two worlds: a trusted environment for sensitive code and data, and a non-trusted environment for regular applications. The processor enforces this separation at the hardware level, so software in the normal world cannot directly read or alter protected assets without crossing defined security boundaries.
In cyber security, TrustZone matters because it helps isolate keys, boot logic, authentication code, and other high-value components from the rest of the system. Defenders use it to reduce the impact of malware, faulty apps, or exposed interfaces, especially in embedded devices where physical access and firmware tampering are realistic threats. In attacks, criminals often try to exploit bugs in the trusted world, weaken the handoff between worlds, or abuse insecure configuration so that the isolation stops protecting what it should.