The boot sequence is the startup phase when a system powers on, loads firmware and core services, initializes storage and network state, and turns on security controls. It is the moment a machine decides what code to trust first, so mistakes here can affect everything that follows.
In cyber security, the boot sequence matters because attackers try to tamper with the earliest trusted steps. If startup scripts, path handling, drivers, or integrity checks are weak, malicious code may load before defenses are active. Common defenses include secure boot, measured boot, signed components, restricted startup paths, and careful validation of any file or configuration read during initialization. Even a small path traversal bug or unsafe absolute path in boot-time logic can redirect the system to the wrong file, alter state, or block startup. For defenders, hardening the boot sequence means treating it as part of the trust boundary, not just routine plumbing.