PDF — Portable Document Format
PDF (Portable Document Format) is a document format created by Adobe in 1993 and now an open ISO standard (ISO 32000). Its defining feature is fixed layout: a PDF describes exactly where every character, line and image sits on the page, so the document renders identically on any device, operating system or printer.
A PDF can contain text, fonts, vector graphics, images, forms, annotations and digital signatures — everything needed to reproduce a finished document faithfully.
What PDF files are used for
- Sharing final documents: contracts, invoices, CVs, reports and official letters
- Print-ready files — what you see is what prints
- Forms that need to be filled in and signed
- Long-term archiving (the PDF/A variant is designed for it)
- E-books, manuals and datasheets
Advantages
- Renders identically everywhere — no font or layout surprises
- Opens on effectively every device, including in every web browser
- Supports digital signatures and password protection
- Compact for text-heavy documents
Limitations
- Difficult to edit — PDFs are designed as final output, not working documents
- Extracting content (text, tables) is lossy and often awkward
- Scanned PDFs contain only images of text, requiring OCR to search or edit
- Complex layouts don't reflow well on small screens
How to open a PDF file
Every modern web browser opens PDFs directly — just drag the file into a browser window. Dedicated readers include Adobe Acrobat Reader, Preview (built into macOS) and countless mobile apps. Editing requires specialised software, which is why converting to an editable format is often the more practical route.