How To Alter PDF Online?
Easy-to-use PDF software
How do I organize .pdf files?
Get an Evernote paid account and you can upload up to 200mb per note. This will cover most text only books and many short and mid length books with graphics. For PDF's larger than 200mb, you will have to split them. Once in Evernote you can annotate, flag, and add notes to your hearts content and you will be completely platform independent. I do this with Android and Windows, but it will work the same with iOS and Mac. A great part of doing this in Evernote is the whole text will be searchable from within EN so you will not even have to remember what book you saw something in to find it.
Alter PDF: All You Need to Know
I prefer this method because I want to use my phone in places that require it, such as public transport, and also out and about, so I don't want to lose it if I take out my car. You can also search for a specific book or topic. Once you create a note in EN, you can save it to an Evernote note, or if you need, you can delete it, with the note you saved containing all the information that you have written in EN. You can also save books to Evernote for offline reading, and if you have it on your phone, you can open a book and search it to find what you need. When you are at home, and can't take your phone with you, you can sync them to your computer and search your Evernote note. I did this with these two books, so I have.