Wait, what exactly makes a PDF document accessible, and how do I know if mine is?

A client wants the 30-page report I made for them to be accessible, and I have no idea what that means for a PDF. Is it just about selectable text, or is there more to it, and how would I tell if mine passes?

had the same thing last month with a planner client. its more than just selectable text, you need alt text for images and the order to make sense for screen readers. i just selected all the text in mine to check the flow. tbh thats what i did and it was fine for them.