What is PDF?
PDF (Portable Document Format) is a file format developed by Adobe in 1992 to present documents consistently across different platforms and devices. It preserves fonts, images, graphics, and layout regardless of the software, hardware, or operating system used to view it.
Quick Facts
| Full Name | Portable Document Format |
|---|---|
| Created | 1992 by Adobe Systems |
| Specification | Official Specification |
How It Works
PDF was created to solve the problem of document portability - ensuring that a document looks the same on any device. The format can contain text, images, vector graphics, fonts, and interactive elements like forms and hyperlinks. PDFs can be encrypted, digitally signed, and password-protected. The format became an open standard (ISO 32000) in 2008. PDF supports various compression methods to balance file size and quality, and can embed fonts to ensure consistent rendering.
Key Characteristics
- Platform-independent document presentation
- Preserves exact layout, fonts, and formatting
- Supports text, images, vector graphics, and multimedia
- Can include interactive forms and hyperlinks
- Supports encryption and digital signatures
- ISO standardized format (ISO 32000)
Common Use Cases
- Official documents and contracts
- E-books and digital publications
- Print-ready documents and brochures
- Forms and applications
- Archiving and document preservation
Example
Loading code...Frequently Asked Questions
What is the difference between PDF and other document formats like Word?
PDF preserves exact formatting across all devices and platforms, while Word documents may display differently depending on the software version and fonts installed. PDFs are designed for viewing and printing, whereas Word documents are optimized for editing. PDFs embed fonts to ensure consistent appearance.
Can PDF files be edited after creation?
Yes, but with limitations. PDFs can be edited using Adobe Acrobat or other PDF editors, but they are primarily designed for viewing rather than editing. For extensive changes, it's often easier to edit the original source document and regenerate the PDF.
How can I reduce the file size of a PDF?
PDF file size can be reduced by compressing images within the document, removing unnecessary metadata, using font subsetting instead of embedding full fonts, removing hidden layers or objects, and using PDF optimization tools that balance quality and size.
Are PDF files secure for sensitive documents?
PDFs support multiple security features including password protection, encryption (up to 256-bit AES), digital signatures, and permission controls that restrict printing, copying, or editing. However, no format is completely secure, and additional measures may be needed for highly sensitive information.
What is the difference between PDF and PDF/A?
PDF/A is an ISO-standardized subset of PDF designed specifically for long-term archiving. PDF/A files must be self-contained (all fonts embedded, no external dependencies), prohibit certain features like JavaScript and encryption, and include metadata. Regular PDFs have no such restrictions.