Organizing gives you every page as a thumbnail so you can rearrange the document by sight rather than by page number. Drag pages into a new order, rotate the ones that came through sideways, delete what should not be there, and download the result as a new PDF. It is the tool to reach for when a document needs several different changes at once — the alternative is running a scan through delete, then rotate, then reorder as three separate passes, re-downloading between each. Everything happens in your browser: the file is read into memory, the page objects are reassembled in the order you set, and nothing is uploaded at any point. Because pages are moved rather than re-rendered, text stays selectable, image quality is untouched and the file size stays roughly where it started.
Working from thumbnails instead of page numbers
Page numbers are a poor interface for a document you have not read recently. Thumbnails show you which page is the cover, which is blank, which one came through the scanner sideways, and where a section actually begins — the information you need to make the decision, rather than a number you have to look up first.
This matters most on scans, where the printed numbering rarely matches the physical positions. Working visually removes the off-by-one errors that come from mixing the two.
Several operations in one pass
Reordering, rotating and deleting are separate tools elsewhere because each is a clean single job. When a document needs all three — the usual state of a freshly scanned stack — doing them separately means three downloads and three re-uploads of the intermediate file.
Doing them together also means you can see the consequences as you go. Deleting a blank page shifts everything after it; if you had noted page numbers for a later rotation, they are now wrong. Working on the thumbnails keeps the document and your intentions in sync.
What is preserved
Page content, embedded images, selectable text and per-page annotations all come across, because the pages themselves are reused rather than regenerated. A rotation applied here is written into the page properties, so it holds in every reader and on paper.
Document-level structure does not survive rearrangement, and could not: bookmarks and an outline tree describe an order that no longer exists. If the document had a table of contents drawn as page content, it is still there and now potentially wrong — worth a check before sending it on.