A system shutdown refers to the process of turning off a computer or electronic device safely. This procedure ensures that all running programs and processes are closed properly, preventing data loss and corruption. It can be initiated through the operating system's menu or by pressing the power button. During a system shutdown, the operating system, such as Windows or macOS, saves any unsaved work and closes applications in an orderly manner. This helps maintain the integrity of the system and prepares it for a restart or complete power-off, ensuring that hardware components, like the hard drive and CPU, are not damaged.