To start off with, Adobe decided that the ability to add bookmarks on a PDF document should only be available to those users who pay. In other words, you cannot add bookmarks in your PDF documents in Adobe Reader. You need to have the editor which is paid. Imagine the pain of reading a thick PDF book and saving the page number manually every time you close the document. There’s another way adding bookmarks in your PDF documents right inside Adobe Acrobat Reader. Here’s how: