I see that there is a sharing option, "Public on the Web -- Anyone on the Internet can find and view":
which can be found in the Google Docs file menu:
as well as Google Drive file options.
I am interested to know the difference between this option and "publish to the web"
My interest is caused primarily by the fact that both options make the document public on the web and indexable whereas I tried the first approach and nobody can explain how indexing works.