Just what is PDF format, how do I view it, and why do people use it?

One of the problems with displaying documents on a computer screen is that everyone's computer is a little different. You see this all the time with web pages - on some computers the screen's a little wider, on others the character size is a little larger, and on others some of the fonts used may not be available at all.

The result is that many documents might look quite different when displayed on your computer versus, say, mine.

Now, in many cases that's ok. For example, if all your document contains is text or words, then the size of the characters, how it wraps on the screen, and even the specific look of the characters is actually not all that important. What matters is what's written, not how it looks.

On the other hand, many documents rely on looking the same everywhere. In fact, that's one of the benefits of paper: once printed it doesn't change, no matter who's looking at it or where.

PDF format tries to solve this problem. A document that has been created in PDF format is intended to look exactly the same everywhere, across all computers regardless of configuration, operating system, or any of a number of other variables.

And perhaps as important, a PDF document should look the same everywhere when printed.

Another advantage of PDF is that you only need a (free) PDF viewer to read a PDF document. If you forward, for example, a Microsoft Word or Power Point document around, you're kind of assuming that everyone has Microsoft Word or PowerPoint. Not only are they not free, but they're quite large and not everyone wants them.

With PDF viewers being nearly ubiquitous, you can create those documents as PDFs and then just about anyone can easily and quickly view them exactly as you expected them to be seen.

That's why many computer and software user manuals and other documents are distributed as PDFs: it's much cheaper to place another file on the disk, and yet you can still count on exactly what it will look like to the user that bothers to open it up. (It seems like paper is particularly wasteful since so many people never even bother cracking open users manuals .)

PDFs are also quite useful for other things. With PDF viewers nearly everywhere now, it's a very convenient container format for documents. For example, I've recently begun scanning paper documents into PDF form and discarding the paper. PDF is likely to be readable on any computer for many, many years to come, and is easy to store and backup. (I use a Fujitsu ScanSnap Sheet-fed Scanner which is incredibly fast and easy.)

But you do need a reader to turn all the resulting ones and zeros inside those PDF files into something you can actually read.

Adobe has readers you can download for many different platforms, and if you're running Windows I happen to be a big fan of Foxit Reader, which is smaller and faster.

Once you've downloaded and installed a reader, you can just double click on those "pdf" documents (or use File->Open in the reader) and you should see the document open up on your screen in a familiar, and readable format.