What is the "Overprint Black" option for?

Question

Working with color

On what example can you understand the principle of its work?

Answer 1

Same as overprinting other colors, only this option will always overprint black globally. Given the peculiarities of some types of printing and the need to do trapping, the function can be useful.
Relevant for prepress and only. For web or other screen graphics, the function is not needed.