OCR = Optical Character Recognition software.
The software can read printed text and take an IMAGE of the text and translate it into editable text then place it into a word processing program (word, etc). SOME OCR software will send the information to PDF, some will not! Usually PDF software is SEPARATE from OCR software.
ALL OF THE SCANNERS I have used (at office and home) came with the ability to scan directly to PDF format! And for PDF, you do not need OCR software!
PDF are often IMAGES of the document so no TEXT reading is necessary to create the document.
If you need people to be able to download, read, print AND EDIT the contents, then you DO need OCR software. If you just want people to download, read and print then you do NOT need OCR software.
Hope that helps to clear it up.
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Over many years, I personally have had three scanners and they came with OCR and PDF generation software of different caliber.
My oldest scanner (did not work with XP) was the best hands-down, with the best software, including a professional version of Textbridge that allowed correction before scanning. Used to scan Insurance docs and WHAT a time saver. Didn't have to type all that legaleze text. Just scan to Word or WordPerfect (was making training manuals) and continue on. LOVELY. That model did not have a feeder. You had to place the docs one at a time on the glass. But even so, I could make multi-page PDF docs with it! You would just define the END of the document after scanning 2, 3, 4 pages and then start a new document.
My newest scanner has the feeder but the OCR software is weaker and does not allow for edit prior to scan. And lost the Textbridge when swapped machines. Could not get it loaded so it could be updated. Bummer.
All of them came with the ability to create a direct to PDF document from the scan without using OCR abilities.