What is the "Placeholder" field for in product "Options"?

[TopWebNames]

What is the "Placeholder" field for in product "Options"?

I can't find it in the Documentation / User Manual; or by searching this forum.

[abantecart]

This is an HTML5 element attribute that allows to put visible text inside form fields

See this:
http://www.w3schools.com/tags/att_input_placeholder.asp

In options, you can specify this if you want text to be inside input field for instance.