Hidden Knowledge creates e-books in several different flavors. Well, actually, different "formats". The format you choose depends on what kind of computer or reading device you use.

All our books are now available in Acrobat/PDF, Palm Reader and Microsoft Reader (LIT) formats; many of them are also available in HTML and Palm DOC.

Everyone can read HTML e-books; they use the same kind of files you read with your internet browser. You can choose the typeface, both the font and the size, by setting your browser's "Preferences" or "Options"; and you can set the size of the page by changing the window. HTML doesn't look as good as some of the other formats, and it's hard to use on small laptops or hand-helds.

If you want the display on your computer to look as much as possible like the page of a hardbound book, with fonts, layout, and appearance of high quality, you want the PDF version. The PDF looks superb on desktop or larger laptop screens, but not as good on tiny screens or hand-helds. The files are larger and take longer to download, because there's more information in them so they can look better. PDF is the best way to handle files with lots of images, though HTML works fine and does the same job you expect from using your browser on websites.

To read the PDF version in all its typeset-like-a-book glory, you need to have the Adobe (aka Acrobat) Reader installed on your computer. If you don't have the Acrobat Reader already, you can get it free from Adobe. It comes in varieties for almost every computer platform, for Macintosh, Windows, LINUX, commercial UNIX (somewhat out of date it seems), or, um, Symbian, OS/2, Palm OS, Solaris, and what-all.

You do need to have version 4.05 or later of Adobe Reader, or the capital "F" characters may be invisible; a bug in earlier versions of their software. Reader is free, and you'll want the latest version anyway. (They're up to version 7 on the Adobe website.)

You can also read the PDF version in Adobe's older eBook Reader. (No longer available from Adobe; it's been merged into Adobe Reader.) The Adobe eBook Reader was formerly available for Windows and Macintosh.

Microsoft has a nice e-book software package called "Microsoft Reader," available for free on their website. It works on desktop and laptop computers, and on some hand-held computers. MSReader files end in ".LIT" and do NOT work on Macintosh or Unix/Linux. They also make the reading easier by hacking with the pixels, using a technique called "ClearType." It helps a lot, and you don't have to know how it works; but you can read what the Seybold analyst said about it on the Adobe website, or go straight to the heart of the beast and see what the excellent Bill Hill has been up to.

Our e-books can be read directly on a PalmOS hand-held, like the Palm Pilot, Handspring Visor, or Sony Clié. All of our books are available in Palm Reader format, which is an elegant solution to reading on a very small screen. With the larger screens now available, Palm Reader books can look really really nice.

Some of our books are also available in the universal-standard "DOC" format and can be read using CSpotRun, iSilo, or eReader/PalmDigital's PalmReader software—all of these available for free on the web. These give acceptable results on all Palm systems and are sometimes the only way you can read on a really small screen.

In the near future we'll also be supplying our books in MobiPocket format. We've have a distribution agreement with MobiPocket but haven't yet done the conversions. MobiPocket is optimized for handhelds, including smart phones (!).

If you have an old Rocket eBook you can upload our HTML directly onto it. The same is true for owners of Softbook readers. (Our HTML files are straightforward and clean, and the ReB utility software has no problems with them.) Or, you can use RocketLibrarian (a free download) to convert it to .rb format. The eBookwise-1150 is a revival of these hardware products, and can read .rb books.

The Franklin eBookMan and the HieBook come with tools to convert the HTML so it can be read on the hand-held. There are other hardware devices about which we know nothing. Well, almost nothing. They can generally use HTML or convert it to a format they can read.

Both HTML and PDF are cross-platform; that means you can read them on Windows PC's, Macintoshes, and Unix/Linux boxes. If you buy the CD-ROM version of one of our books, you get all currently available formats on the same disk, and it's ISO9660 compatible (which means you can read it on essentially any kind of computer).

Enough of the technical stuff! Buy the book the way you want it.