[Tex/LaTex] How to insert a border below text

formattingrules

I want to emulate a feature from a few word processing programs (e.g. Microsoft Word, LibreOffice Writer) where I could (somewhat) arbitrarily insert a bottom border below any text/paragraph. How can I do this in LaTeX?

Edit: Just to clarify, what I want is pretty much a horizontal line across the page just below the text. Like this:

Bottom border

Best Answer

There are probably many ways to do this. Have you tried issuing the command

\hrule

on a line by itself?