Windows System Tray Link

At a minimum, Windows always displays critical system icons: the clock/calendar, network (Wi-Fi/Ethernet), volume, and power (on laptops). These provide instantaneous, real-time feedback about the machine’s core state. A red "X" on the network icon signals a loss of internet; a crossed-out speaker indicates mute; a low battery icon warns of imminent shutdown. This at-a-glance awareness is the tray’s most fundamental value.

You can choose which icons stay visible and which stay hidden: windows system tray