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Glossary
PDF terms, in plain English
20 terms, each defined in a sentence you could read aloud, then explained properly.
PDF vocabulary gets in the way at exactly the wrong moments — when a portal rejects your file for a reason it will not explain, or a colleague asks whether you redacted something or only covered it. Most of these words describe one specific thing, and knowing which one turns a vague problem into a fixable one.
Each term below is defined in a single sentence first, then explained in terms of what it changes about a real document: what you would see, how to check it in your own file, and what it costs you if you get it wrong.
C
2- Security & Privacy
Checksum
A short fingerprint calculated from a file’s bytes: identical files give the same value, and a single changed byte gives a completely different one. - Merge & Organize
CropBox
The rectangle of a PDF page that readers actually display. Cropping changes it without deleting anything outside it.
D
1E
1F
1L
1O
2- Security & Privacy
Owner password
A password that leaves a PDF readable but marks printing, copying or editing as not allowed. Readers honor it by convention, not by cryptography. - Repair & OCR
OCR
Reading the letters in a picture of a page and storing them as text, so a scan becomes searchable and selectable.
P
8- Security & Privacy
PDF metadata
Fields stored with a PDF but never shown on the page: title, author, the software that made it, and the dates it was created and changed. - Security & Privacy
PDF encryption
Scrambling a PDF’s contents so it can only be read with the right password, using AES-256 in any file made this decade. - Security & Privacy
PDF form fields
Interactive boxes, checkboxes and dropdowns layered over a PDF page, holding values separately from the page itself. - Merge & Organize
PDF bookmarks
The clickable tree of headings shown beside a PDF, each entry jumping to a place in the document. - Merge & Organize
PDF page size
The dimensions of a page in points, stored per page: A4 is 595 × 842, US Letter 612 × 792. A single PDF can mix them. - Office Convert
PDF/A
A restricted version of PDF made for long-term archiving: everything needed to display the file must be inside it, and nothing may depend on outside resources. - Security & Privacy
PII (personally identifiable information)
Any information that identifies a person, alone or combined with other data: a name, ID or account number, address, phone number, email address, face or signature. - Scan & Create
PDF
PDF stands for Portable Document Format: a file that keeps a document looking exactly the same on every device, with its fonts, images and layout locked in place.