One of the first challenges you'll encounter with Linux is trying to find that wysiwyg word processor you were used to under Windows, or one like it. You probably won't find it. Yes, WordPerfect for Unix does exist and can be made to run under Linux by using iBCS libraries, and there are a couple or three other Word Processing programs out there that will work, but realistically, Word Processing isn't done in Unix. The basic philosophy is quite different.
Unix has been around for quite a while, and the ideas that grew up with it have likewise been around for quite a while. One of the most important ideas involved in text processing has been to stay away from proprietary file formats that only specialized software can read and in stead rely on plain ascii text files with special codes to enable a post processor to produce formatted output. The ascii files thus become a source file and the formatted output becomes the target file. Much like programmers create a program's source code with a text editor but compile that source into a binary executable. Text processing in Linux is a similar adventure.
On the PC platforms, text processing originally was done. Remember Word Star? Remember the dot commands that would insert formatting commands to the printer? That was as recent as the early-to-mid eighties. But anyone could open one of those files because they were simple ascii Radix 64. You could view them with vi or with emacs. But when competition for marketshare caused some companies to focus on proprietary file formats rather than straight ascii file saves, things changed. Now, in order to read a file created in WordPerfect, you had to have a copy of WordPerfect. You could save as ascii, but then you would lose your formatting. This migration to the "word processor du jour" was the beginning of the end.
Somehow, the mentors of computing failed to communicate the importance of standards to the computer proletariet. Everyone with a PC became armed and dangerous. They could create files in their proprietary format of choice, and they changed the computer market. Now that everyone could buy a computer with a word processor, whether they understood the importance of sharing resources or not, they voted with their wallets and created history. Now, it didn't matter whether everyone else could read your files; as long as you wrote your documents with the most popular word processor, that was good enough. Now, we're left with the fallout of the computer wars and the word processor campaigns, and we're forced to translate files from one proprietary file format to another.
Let's say MS Word isn't your favorite word processor. Let's say, for some strange reason, you like DeScribe. (Trust me, there are other good alternatives to Word.) Now when you want to share files with someone else, you have to translate back and forth between *.doc for Word and *.doc files for DeScribe. That's because the formatting is done with proprietary markup on the file itself. And, it requires a proprietary viewer that both edits and views the file. This was the result of a new software industry competing for dollars from the new computor proletariet of the mid-eighties. And things have only gotten worse. Unix doesn't suffer from this problem so much.
Linux, which you know by now is a Unix clone like HP-UX or AIX, inherits the legacy of information sharing that came from the early computing visionaries and professionals, long before micro computers became popular. Standards were agreed upon in order to enhance cooperation. Competition took place within the limits of the standards. This way, cooperation by sharing information took precedence over competing for the dollar.
The text tradition of Linux specifies one universal file format which anyone can access with their favorite text editor--ascii. A single text editor can be used to write books, create programs, modify system configuration files, and write poetry. If you like vi or emacs or jed or any of the other popular text editors available for Linux, you can use it for just about everything, if you want.
That's because of standards. Format is added to the document by formatting instructions inserted into the text itself. These commands are interpreted by the post-processing engine to produce the final output. The advantage of standards is that since anyone can read the source file, any programmer can extend the processing engine with added features and custom capabilities. You don't have to wait for a single commercial software vendor to upgrade anything. Since the file format and the formatting instructions are in the public domain, you can roll your own post-processing engine or use someone else's. It's up to you.
Naturally, the output file depends on what formatting language you chose to format the source file with. The two most popular are probably TeX (pronounced "tech") by Donald Knuth and the long-standing troff formatting system. SGML (Standard Generalized Markup Language) is another possibility, but it is more suited for highly structured documents that must maintain their structure through complex document transfers. It is more for structuring documents than formatting them, though with the recent completion of the DSSSL (document semantics and style specification language) formatting SGML documents with style sheets is now practical.
Most Linux distributions include one or more TeX and troff packages. Using them, you can format documents and chose from numerous processing programs to produce output files in many formats. You can create one source file in ascii, and that can be your base file format. From that, you can output to PostScript, groff, TeX, LaTeX (an extension to TeX), sgml, html (an application of sgml), dvi (device independent file format), rtf (microsoft's proprietary transfer file format) or even other formats that you've possibly never heard of. Because the source files are ascii, you can extend the possibilities without limit.
If you're coming to Linux from the word processor world, you'll probably have some adjusting to do. The nice thing about learning TeX or groff (the GNU version of troff) is that once you've learned them, you won't have to learn them again. If the leap is too much for you to make, you can always get WordPerfect for Unix or Applixware, or one of the other proprietary word processors available for Linux.