Work with PDFs. Know what you're doing.

Page order, file size, and whether the PDF still reads clearly all matter when you put together an application, a quarterly report, or a portal packet. A submission system can reject a file that is out of sequence or over the size limit.

Decide what comes first: cover letter, main report, then exhibits. After you merge or compress, open the result and check footnotes, signatures, and small table text.

If you are sending this to a university, a hiring portal, a grant desk, or an internal review folder, name the files before you combine them. Keep a copy of the originals. Scroll the first page of each section in the result before you upload.

A scan is often a picture of a page, not selectable text. That is why you cannot highlight a paragraph in some PDFs, why search finds nothing, and why copy and paste returns a blank. Camera photos of letters, faxed forms, and older photocopies behave the same way.

OCR can add a searchable text layer. Adobe notes that OCR can make text searchable, and that you should review the output. Handwriting, stamps, low contrast, and skewed pages often produce errors.

Treat OCR as a first pass. Search for a name or invoice number you know is on the page. If the result is garbled, rescan at higher contrast before you quote, index, or edit from the file. Searchable text does not make a document accessible on its own.

Comments, revision history, attachments, and document properties can travel with a PDF even when they are not visible on screen. A black rectangle drawn over a name does not remove the text underneath.

Adobe's redaction workflow includes an option to sanitize hidden information. Use that kind of step when you are sending a contract, an invoice, a case note, or an internal draft to someone outside the original review circle.

Before you attach the file, search for account numbers, project codenames, and personal names. Open the properties panel. If you keep an unredacted archive copy, store it separately. Redaction on the exported file is not meant to be undone.

Reading order and document structure affect keyboard and assistive-technology users. A file can look correctly designed on a large monitor and still jump around when someone tabs through headings, lists, or form fields.

W3C guidance on PDF reading order is clear on this point: visual layout is not the order the file is read. Headings, lists, and language settings have to be present in the structure, not only styled to look like headings.

When the audience is the public web, PDF is not always the best primary format. GOV.UK accessible publishing guidance favors HTML where possible, and using PDF as a downloadable alternative. If you do ship a PDF, check it with a keyboard and, where you can, with the same tools your readers use.