PDF File Format (.pdf)

A PDF file records each character, image and line at a fixed position on the page, independent of any word processor's styles or fonts, which is what makes it print and display identically wherever it opens.

.pdfDocuments

PDF at a glance#

Full name	Portable Document Format
File extension	.pdf
Category	Documents
Developer	Adobe
First released	1993
MIME types	application/pdf
Compression	Lossy or lossless, depending on how the file was written
Specification	ISO 32000-2:2020 (PDF 2.0)
FileFlip support	FileFlip reads and writes this format

What a .pdf file can hold#

These are the things a PDF file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.

Embedded metadata	Yes
Multiple images or pages	Yes
Selectable text	Yes
Encryption	Yes
Human readable	No
Comments	Yes

Strengths and limitations of PDF#

What PDF does well

Renders identically on every device and printer, because every mark on the page has a fixed coordinate rather than a position implied by a screen size
Embeds the fonts it uses, so text displays correctly on a machine that doesn't have them installed
Supports 256-bit AES encryption with separate owner and user passwords, built into the format itself
Opens without installing anything, since every modern browser has a built-in PDF viewer

Where PDF falls short

Stores where each character sits on the page, not how the text is structured into paragraphs and headings, so recovering that structure on conversion is a best-effort guess and never a perfect reconstruction
A scanned page is saved as a picture of the page, not as text, so nothing in the file can be selected, searched or copied until a separate OCR pass runs on it
Editing text in place needs the original source document or dedicated PDF-editing software, not a text editor
Multi-column layouts and tables frequently come apart when converted into an editable format

Use PDF to send a finished document to someone who needs to see the exact layout, on any device, without being able to accidentally change it.

Convert PDF to DOCX or another editable format when the real task is changing the wording, not just reading it, and accept that the layout will reflow rather than stay pinned in place.

How to open a .pdf file#

A .pdf file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts PDF into a format your machine already opens, and it does it in the browser tab rather than on a server.

Platform	Programs that open it
Windows	Adobe Acrobat Reader, Microsoft Edge, Foxit PDF Reader
macOS	Preview, Adobe Acrobat Reader
Linux	Okular, Evince, Xpdf
iOS	Files, Adobe Acrobat Reader
Android	Google Drive, Adobe Acrobat Reader
Web	FileFlip, Google Docs

PDF questions people ask#

Does converting a PDF to Word preserve the original layout?

No, it reflows rather than preserves. A PDF fixes every line of text and image at an exact coordinate, while a Word document flows text into paragraphs and pages that adjust to fit, so a converter has to guess at paragraph breaks, headings and reading order from position alone. Simple single-column documents come through close to intact; multi-column layouts, text boxes and tables often don't.

Can a scanned PDF be turned into editable text?

Only through OCR (optical character recognition), which reads the shapes of letters in the scanned image and turns them into actual text characters. A scanned PDF has no text in it at all, only a picture of a page, so a converter that just changes the file format has no words to extract until OCR has run as a separate step.

How do I make a PDF file smaller?

The biggest reduction usually comes from recompressing or downsampling the embedded images, since photos at print resolution are the main thing bloating most PDFs. Removing embedded fonts you don't need, flattening unnecessary layers, and stripping metadata help further, though they save far less than the images do.

Why can't I select or search the text in some PDF files?

That happens when the PDF is a scan: the page is stored as an image, so there's no text underneath to select. A PDF built from a word processor or web page instead embeds real text, which is why selection and search work on some PDFs and not others that look identical.

What's the difference between a regular PDF and PDF/A?

PDF/A is a restricted subset of PDF built for long-term archiving. It bans features that depend on something outside the file, like links to external content or non-embedded fonts, so a PDF/A file is guaranteed to look the same decades from now, even after the software that made it is gone.

Converting PDF files#

Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.