The regular TeX (and LaTeX) typesets text from left to right, so it is not suitable for typesetting Hebrew texts.
An additional version of TeX, called eTeX (For Extended TeX) is now available for both Unix and DOS/MSWindows. eTeX has right-to-left, as well as left-to-right capabilities. Actually, eTeX can either work in compatibility mode, which means working exactly as the regular TeX system, or work in extended mode, which means working in right-to-left mode as well as in left-to-right mode. From this it is clear that for Hebrew typesetting, we have to have eTeX working in extended mode.
After installation of eTeX, you have, apart from the regular TeX and LaTeX, two new commands -- etex and elatex, both working in extended mode. Those commands are sometimes referred to as TeX--XeT and LaTeX--XeT, respectively.
The fact that the program works in extended mode is manifested by a message you get on screen after you activate the program (eTeX or eLaTeX). You get the message
This is e-TeX, Version ............
entering extended mode
The right-to-left mechanism which is embedded within eTeX has been written and donated by Peter Breitenlohner from Germany.
Having a working right-to-left TeX system is essential for typesetting Hebrew texts, but it is not enough. You must also have Hebrew fonts, as well as one or more files containing definitions (=macros) which facilitate the usage of right-to-left typesetting for Hebrew texts.
The fact that there is more then one representation of Hebrew letters within computer systems makes this issue somewhat complicated. Fonts are available in a number of variations, and, accordingly, there are versions of macros files which pertain to the fonts' variations. However, things have become simplified lately, with the addition of a working Hebrew system within latex2e, where you use the same macros for all available variations of Hebrew, and you specify the relevant Hebrew variation by using the appropriate value of a parameter.
No matter which Hebrew format you use, or whether you work with etex or with elatex, the preparation of your input file is similar.
You prepare the text using any editor which can type Hebrew letters. Some editors display Hebrew text in a logical order, where you see the Hebrew words reversed; others display it in a visual order, that is, Hebrew words look ok, from right to left. However, it is important to note that within a tex/latex Hebrew input file, words should be typed in their "natural" order, no matter if the text is in Hebrew or not; and, if you display the raw input file on screen "as it really is", Hebrew lines as well as separate Hebrew words will appear "reversed".
There is also a TeX-XeT for Macintosh, called DirectTeX. Click for explanation concerning Hebrew TeX on Mac
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