PDFs have become the default format for sharing formatted documents across platforms. If you only want to read PDFs, iBooks will likely meet your needs. But, if you want to modify or annotate your PDFs, you’ll need a different app with a larger toolkit. The AppStore has many options, but they all have such similar descriptions that it can be difficult to determine which one has the features you need. At the very least, all PDF annotators should allow users to underline, highlight, or strikethrough text, add a note, and write on the PDF (preferably via both keyboard text and handwriting). This AppGuide includes apps that do all of that and more, so that your iPad can be your first choice when you need to annotate a PDF.