If you have ever been reading a PDF and wanted to be able to find information beyond using ctrl f to find a word, give Chatpdf.com a try.
Once you upload the PDF you will receive a brief summary along with some questions that chat feels as though are pertinent.
Below that you will see the ability to ask any question you would like. This is huge as you can ask it to find any information within the PDF, ask for a summary, pretty much anything you can think of.
Embedded below is a 2 minute and 18 second YouTube tutorial.