I highly recommend LaTeX, (pronounced lah-tekh and not like a BSDM costume). Originally TeX, written and developed by Stanford professor Donald Knuth, to help with typesetting. LaTeX came later, developed by Leslie Lamport. LaTeX came as a macro package involving the TeX command structure to help for better formatting for documents involving mathematics, which tend to use non ascii symbols and notations, in addition to formatting that is incredibly difficult if not impossible to type out using normal systems. LaTeX can also be used to perform tasks that would be included in a MS Word program such as indexing, citation, etc, it is possible to compose an entire document in LaTeX and it can be used on all platforms including Windows, Mac and Linux, just be sure your recipient does not expect it in Word.

Since then LateX has benefited from a variety of contributions and additions from numerous authors, which have now evolved into a combination of TeX and LaTeX distributions, not so different from the organic development of Linux.

Execution of LaTeX looks similar to old typing programs where formatting occurred written directly with instructions directly notated within the text to execute as commands, making the learning curve similar to a computer language. It can be written from within a text editor and must be run to show output.