Do you use PDF files or read documents in PDF format? Even if you don't use them regularly, I'm sure that you've come across a PDF file or two in...
Personally, I believed that the iPad would allow me to annotate PDF files exactly the same way as I was used to do it on paper copies: by squeezing handwritten notes into the upon reflection, this is actually not the best idea.
Annotating a text means that you take notes in the margins and make other markings for reading comprehension. Many people use annotation as part of academic research or to further their understanding of a certain work. To annotate an article, you'll need to ask questions as you go through the text, focus on themes, circle terms you don't understand, and write your opinions on the text's claims. You can annotate an article by hand or with an online note-taking program.
This routine has helped me many times when receiving drawings from others that include annotative blocks and text, you may not need as many scales that are applied to these annotative objects.