The reason Google’s background can appear black is due to the use of "dark mode" or "dark theme" settings. Dark mode is a color scheme option that changes the background interface to black or very dark colors to reduce eye strain in low-light environments and save device battery. This setting can be enabled manually by users on Google Search, Google Chrome, or through device- level themes or power-saving modes that switch the background to black automatically. Sometimes, Google or browser extensions also trigger dark backgrounds. In rare cases, black backgrounds may appear due to glitches or conflicting browser extensions. Users can switch back to the usual white background by changing the appearance settings in Google or the browser settings, or by disabling dark mode or related extensions.

Thus, Google’s black background is not the default but a user or system- configured dark mode feature designed for visual comfort and energy efficiency.