The phrase "true black" refers to the color black in its purest and darkest form, without any tints or shades of other colors mixed in. Full definition
You can also shoot in true black - and - white, which can make for pretty dramatic results. (tomsguide.com)
With an OLED, some pixels can be turned off, allowing for true black. (fortheloveoftech.com)
The rising popularity of OLED technology isn't surprising: after all, compared to LCD, OLED screens are more vibrant and saturated with true blacks. (androidauthority.com)