Do I need Adobe Reader? Or Acrobat Pro? How do I edit PDFs?
PDFs are like food to a Mac. Whenever you print anything from a Mac, you’re creating a PDF. That’s why, whenever you go to File > Print, there’s a convenient PDF menu at the bottom left, with options like Save As PDF… and Mail PDF.
The Mac has an built-in app called Preview, which works with all kinds of image files, including PDFs. With Preview, I can sign PDFs with my signature, or notate the heck out of them.
Depending on what you do to/with PDFs, you might use Preview, or the even more awesome PDFpen, which can change text in a PDF, or the super badass PDFpenPro, which can teach your PDFs to sit up, beg, and roll over.
PDFpen can even read the text in a PDF, or turn a PDF into a formatted Word doc. It’s very powerful, and a fraction of the price of Acrobat Pro (which is still great if you do prepress).
PDFPen is also great on the iPad and iPhone.
I use GoodReader for my PDF reference library, with all my manuals and training documents and other legibles. It also has robust commenting and markup features.