White screen of death explained
A blank white screen means something stopped before it could draw anything. What stopped, and why, depends entirely on where you are seeing it.
On a phone
A white screen on a phone is most often a hardware connection problem: the display ribbon cable has worked loose, usually after a drop. The panel is receiving backlight power but no image data, so it lights up white with nothing on it.
Try a forced restart first — the button combination varies by model, and it costs nothing. If the phone vibrates, rings or responds to touch while showing white, the system is running and only the display connection has failed, which is a repairable fault and usually not an expensive one.
On a Windows PC
A white screen at boot or during use generally points at the graphics driver or the display connection rather than at Windows itself. Boot into safe mode; if the screen is normal there, the driver is at fault, and a clean reinstall of the graphics driver is the fix. If safe mode is white too, work through the cable and monitor checks — a second display or a different cable will settle it quickly.
On a Mac
A white or light grey screen at startup typically indicates the machine cannot find or load a valid system. Resetting NVRAM and booting into recovery are the standard first steps. If recovery loads normally, the hardware is fine and the problem is on the system volume.
On a website
The classic white screen of death in a browser is a server-side error where the application crashed before sending any output, and error display was switched off — so you get an empty page rather than a message. In PHP applications and WordPress in particular, this is usually a fatal error from a plugin, a theme, or an exhausted memory limit.
The diagnostic path is to enable error reporting or read the server error log, which will name the file and line. Failing that, disable plugins in bulk and re-enable them one by one, or switch to a default theme to isolate the cause. A memory exhaustion message means raising the memory limit, not disabling anything.
Telling a fault from a page
One useful check: if you can see a white screen and your cursor still moves normally over it, and other applications respond, the display hardware is fine. A genuine panel fault does not care which application has focus. If the whole screen is white in every context including the boot logo, it is hardware.