Something to use for headings perhaps, and not so much for common text. It is done by creating a container with a gradient background, and then adding some text (here H1 and H2 have been used) in black with a white background. The magic happens when you turn on 'blend-mode: screen'.
Instead of a gradient background you can also use an image background.
Unfortunately, IE11 doesn't understand the blend modes and is displaying just the black text.