PDF (Portable Document Format) is a file format intended to ensure that documents can be exchanged reliably, independent of the type of software or hardware being used to view, print, or edit them. In this Rocket Yard guide, we’re going to explore the Preview app’s ability to fill out PDF forms and mark up files, even files that weren’t designed to be completed electronically. It includes a number of features and services that can be used for editing PDFs, working with images, even creating electronic signatures to use to sign important documents. Preview, the free PDF viewing app included with the Mac, can do a lot more than view images or open PDF files to view.