File format
There are a number of different ways text can be stored on a Palm computer. Unless you start reading ebooks in some proprietary format, you'll only have to deal with two major formats and a few variants. Before we outline these formats, we should probably gain a basic understanding of how ebook files work on a Palm handheld.

For starters, you must realize that there are no files on the Palm OS. Everything is stored in some form of database or another. The difference between the "file" formats is in the structure and capabilities of the database format. Most of the ebooks you'll read with your Palm handheld will be in the Palm DOC format. This format exists to overcome the Memo Pad's 4KB limit. It does this by creating a string of 4KB database records that combine to make one "file." The Palm DOC format is open source, and it's only capable of encoding ASCII characters, so there aren't any bold, italic, or underlined characters in a Palm DOC file.

A number of ebook sellers and distributors have customized the open source Palm DOC format to include more features; most noticeably, text styles and Digital Rights Management (copy protection). These souped up versions of Palm DOC in most cases have a specific and proprietary reading program. While no one strain of Palm DOC is all that much better than another, they do tend to be incompatible, and a choice to use one over the other usually is the result of available reading materials rather than an actual feature comparison.

There are at least two other major formats that you'll probably run across at some point. They are iSilo (at http://www.isilo.com) and TomeRaider (at http://www.tomeraider.com). iSilo was created in response to Palm DOC's lack of rich text styles and poor compression. iSilo can store nearly all of the formatting of an HTML file and the compression allows large documents to be stored. TomeRaider is notable because of its ability to compress very large documents into files that can fit on a handheld computing device.

There are a number of other formats that you'll run across, but these will work for most of the ebook reading you do. Even though there are only three major formats, there are far more than three major reading programs. Rather than give an overview of each of the many available readers (which you can find at http://www.memoware.com/mw-helpf.htm), I'm simply provide an overview and my personal favorites.