While this is mostly true, it should not be relied on. If the PDF is produced from a text document or report generator, then the text as well as the charts are easy to edit with any text editor (only requires decompressing the PDF first). Obviously different if the document is a scanned image, but just saving a Word doc into PDF does not make it a read-only file.
The benefit of PDF is that it is (as the name suggests) portable, and one knows that the recipient will see exactly what was sent. With a Word or Powerpoint, formatting can show up different on different machines, fonts may not be available, etc.
When you print a word document to PDF the actual text, placement, and fonts are all embedded in the pdf. It may have been designed for publishing, but it's pretty simple to edit text in it.
Editing stops being simple when you have to deal with reflows and boundaries. In general it doesn't really work, at least not for any complex documents.
Yes, and following this logic, anything can be called editable. A binary file is 'editable' with enough work. The point is that PDF is the format used to disseminate private information to multiple and disparate parties with the confidence that will all receive the same informtion, and cannot (reasonably) change that document.
That's why it's used in marketing for things like lookbooks and elsewhere for things like contracts, that are read-only by design and should never be edited by anyone but the entity that wrote it in the first place.
In the case of PDFs, though, it is almost trivial to edit. Uncompress the PDF, and then search in a text editor for the sentence you want to change and edit it. Uncompressing takes one command, and after that it is almost as easy as editing a word doc (in your favorite editor, search and replace the text you want to change)
It's a little more complicated but not difficult to edit charts.
Trivial for you, impossible for the likes of marketing execs, lawyers, etc. As far as most laymen are concerned PDF's are completely unchangeable, and even those that know you can edit it, don't know how to do it themselves and tend to ask someone else. That's in my experience anyway.
