I Need a Textbook Reader Application That Supports Note Taking?

I need a textbook reader application that supports note-taking, searching, highlighting, and organizing books of any format (EPUB, PDF). Does this exist?

Well of course there is not just one but many PDF reader tools which you can use to highlight text and add notes to a PDF document. One such popular, easy to use and reliable PDF reader tool is Wondershare PDFelement. You can use PDFelement on Mac, Windows, iOS and Android based devices for highlighting text and adding notes which is basically called Annotation. In this answer I will list the steps on how to annotate PDF on iPad. So, here you go. Install and launch PDFelement app on your iPad first. After that select to import the PDF file that needs annotation. Once the PDF file is uploaded, simply tap on the "Markup" button. This will open up the PDF annotation tool menu. You can then make use of available tools to highlight text and add notes to your PDF document/file. After making all the annotations, simply save the PDF file by clicking “Save” button as shown in the below image.