PDF file format
Portable Document Format
PDF is the universal document format. It keeps layout, fonts and images identical on every device and printer, and can contain many pages of text, vectors and images.
| Property | |
|---|---|
| File extensions | |
| MIME type | application/pdf |
| Introduced | 1993 by Adobe (ISO 32000 since 2008) |
| Compression | Per object: Flate (lossless), JPEG, JBIG2 and others |
| Transparency | Yes |
| Animation | No |
| Colour depth | RGB, CMYK, greyscale, spot colours |
| Support | Universal — every OS, browser and printer |
| Best for | Documents, forms, printing, sharing |
What is a PDF file?
PDF (Portable Document Format) was created by Adobe in 1993 to make documents look identical on every computer and printer. It became an open ISO standard (ISO 32000-1) in 2008, and PDF 2.0 (ISO 32000-2) followed in 2017.
A PDF is a collection of objects — pages, fonts, images, vector drawings, annotations and form fields — each compressed with a suitable method. Text is usually stored as real characters with embedded fonts, which is why PDF text is selectable and searchable, while scanned documents contain only images of text.
Strengths and weaknesses of PDF
PDF preserves exact layout, prints predictably, supports multiple pages, links, forms, signatures and encryption, and opens in every browser. It's the expected format for contracts, applications, invoices and official forms.
PDFs are hard to edit compared with word-processor files, and scanned PDFs can be very large. Their content can't be dropped into image-only places like social media posts without converting pages to JPG or PNG.
Working with PDFs in your browser
Fylo's PDF tools merge, split, rotate and compress PDFs and convert between PDF and images entirely on your device, using the open-source pdf-lib and Mozilla pdf.js libraries. Your documents are never uploaded.