Most, if not all of you, have used PDF files at one time or another. Your use, however, is likely to have been limited to opening and reading a PDF file that someone sent to you. For those of you who are scratching your heads and asking yourselves what a PDF file is, read on. Portable Document Format (PDF) is a file format developed by the computer software giant, Adobe Systems, “…to present and exchange documents reliably, independent of software, hardware, or operating system.”

PDF files can be viewed using free Adobe Acrobat Reader software, which is likely what you have used. The PDF files that you have used may have included all sorts of legal documents and publications. Even if the practice of law is no longer your principal reason for using PDF files, the opportunities for personal use are endless.

It is one thing to simply open and read a document that exists in a PDF format. You can take your use of the file to a higher level, however, with an app that will allow you to not only open and store the file, but to annotate, highlight and work with the PDF file on your mobile device. Having this capability is essential to realizing the full capability of the medium.

The app that I prefer for this purpose is PDF Expert 5 by Readdle, which is reportedly the most downloaded PDF management app for the iPhone or iPad. At $9.99, it is somewhat more expensive than many apps, but remains a bargain when you consider that PDF Expert lets you view, annotate and edit PDF documents, as well as highlight text, make notes, draw with your finger and save these changes. This app is also the only iPad application that can fill in PDF forms.

To whet your appetite, the following is a list of some of the app’s features:

• PDF Expert reads almost all document types, such as MS Office, Power Point, text files, images, and even music and video files.

• PDF Expert can retrieve documents from desktop computers, e-mail attachments, and other apps such as Dropbox and GoogleDocs.

• You can add electronic sticky notes to a document, and when you use PDF Expert in its review mode, the app allows you to add in-line annotations to a text of the PDF you need to review.

• With PDF Expert, you can mark the status of documents as you once did with a rubber stamp; e.g., “draft,” “confidential,” or “final.”

• You can type text, fill out forms, sign documents electronically with your finger, and print completed forms from within the app.

• PDF Expert allows you to add or delete pages in a PDF document, re-arrange pages or remove specific pages from the file, copy and paste pages between different PDF documents, and extract pages to save as a separate PDF file.

I make it a habit to save PDF file documents on my iPad, using the PDF Expert document management feature, for use in court or in meetings. Once I have stored a document on my iPad, regardless of whether it is an annotated document or simply one that I am saving in its original form for future reference, I don’t have to be concerned about internet connectivity when I later need it. The document is ready for viewing with a few taps of the finger as long as my battery power holds out.

GoodReader by Good.iWare ($4.99) is another very similar app that deserves your attention if you’re shopping. A comparison of the features between these two programs is beyond the scope of this article, but suffice it to say that they are both excellent apps. Most of us barely take advantage of the power that our computer software has to offer, and that is no less true when it comes to utilizing the many features that PDF Expert has to offer.

Finally, we don’t all use IOS devices, so you need to know that two of the top PDF management apps for android devices are PDF Max and Foxit MobilePDF. Also, PocketBook Reader is reportedly great for note-taking on android devices. 