When you see light text on a dark screen, its edges seem to bleed into the black background. This is called the halation effect, and it reduces the ease of reading. Remember, the eye is made up of ...

In the early days of personal computing—think UNIX early—text was often white or green on a black screen. That didn't last long, of course, but there's a ...

Dark mode is a specific setting on a mobile device, tablet, laptop or computer, that changes the default, white or light, screen background to a darker colour (typically dark grey or black).

The TL;DR is that high contrast between background and text colors is important, and that for many users, black text on a white background is a) most legible and b) most professional-appearing.