This page is intended for the many people wishing to use Gregorio but not yet acquainted with TeX. For the installation of TeX and GregorioTeX system, refer to the installation page.
What is TeX?
TeX (pronounced tek) is a language created by Donald E. Knuth in 1977, for the purpose of creating documents. In one sense, it is a non-graphical program for text processing (in contrast with MS-Word, for example, which is a graphical program). To clarify, one creates a text file containing the desired text of the document and formatting commands (setting this portion of text in bold, another portion in italics, changing the font, the spacing, etc.). One invokes LaTeX on this text file, and LaTeX will produce a PDF file or DVI file (a format easily convertible into Postscript or PDF).
The trouble with TeX is that it is a rather complex language, whose learning curve is acknowledged to be a bit long. The advantage is, however, a rendering very often nicely superior to other text processors, notably for example in the rendering of mathematical formulas, a field in which there is really no competition. As well, TeX has the advantage of being extremely programmable.
LaTeX is a more expanded collection of very-high-level macros (and therefore easier to use). GregorioTeX is programmed in TeX, so its code can be used in LaTeX and Plain TeX.
Why did you have to use TeX?
The first reason that impelled me to use TeX is that it's a free (non-proprietary) language (in the public domain), ported to various OSes, and capable of producing these types of scores. The aim of gregorio is to be usable by everyone freely and without charge, and thus that excludes proprietary commercial software for computer-aided publishing. So aside from TeX the choice was quite limited, since there are very few text processors as programmable (making Gregorian chant scores is less easy than it might appear).
Furthermore, TeX can be used to produce complete books of professional quality (cf. examples), so using TeX does not reduce the possible usages of gregorio.
Why and how to learn LaTeX?
Even if theoretically you won't have to modify the TeX files produced by gregorio at all, or perhaps very little, it is necessary for you to have at least some idea of the basics in TeX to understand and modify them. Moreover, I eagerly encourage everyone to graduate to LaTeX, because even though it is more complex than point-and-click desktop publishing software, you will not be disappointed with the result.
Be aware in advance that learning LaTeX will demand of you time and energy. When you're used to software with a graphical interface, it is easy to be disoriented or discouraged at the learning curve of a language such as TeX. In the meantime, after some effort at the outset, the language reveals itself to be very powerful and the renderings more than satisfactory.
To learn LaTeX, a lot of tutorials are available on the net, as well as several excellent books. Here is an example of a tutorial.
What are the different versions of TeX?
What we usually call TeX, is in fact a combination of a format, written in TeX (usually Plain TeX, LaTeX or ConTeXt) and an engine, the executable file (TeX82, PDFTeX, XeTeX or LuaTeX). Gregorio actively uses the features of LuaTeX.