"Split a PDF" can mean several different jobs. You might need one page out of a 200-page contract, every chapter as its own file, or a document cut into pieces small enough to email. Each has a tool built for it.
Pull out specific pages
If you only need a few pages, Extract Pages is the quickest route. Enter the pages you want, such as 1-3, 7, 12, and you get one new PDF containing just those pages. The original stays untouched.
Cut into several files
Split PDF divides a document into multiple files at the points you choose, or into fixed chunks of a set number of pages. Multi-file results download together as a ZIP.
Stay under an attachment limit
Split by Size fills each output file with as many pages as fit under a target size. It is the practical choice when a mail server or upload form rejects anything over 10 or 25 MB.
Split by chapter
Reports and ebooks exported with a table of contents usually carry bookmarks. Split by Bookmarks uses them as cut points, so each chapter becomes its own file, named after its bookmark. If the PDF has no bookmarks, add them first with Add Bookmarks or fall back to page ranges.