A state transition is a device changing from one mode to another, such as sleep to wake, closed to open, or locked to unlocked. Security-sensitive products often depend on many transitions, and each one has to be validated by firmware, the operating system, and the application layer.
In cyber security, state transitions matter because attackers often look for gaps between modes. A device may trust different inputs when it wakes, folds, rotates, or opens a camera, and those moments can expose bugs in authentication, permission checks, or sensor handling. Defenders focus on strong state machines, secure defaults, and clear indicators so the device only accepts the right actions in the right mode. Good design reduces accidental input, prevents silent mode changes, and makes it harder for malicious software or physical tampering to exploit edge cases.