Portable Document Format
The Portable Document Format (PDF) is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. Based on the PostScript language, each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, vector graphics, raster images and other information needed to display it.
History & Origin
Created by Adobe Systems in the early 1990s, PDF was designed to solve the problem of sharing documents between different computer systems and operating systems. In 2008, Adobe released PDF as an open standard (ISO 32000-1:2008), allowing anyone to create software that reads and writes PDF files without paying royalties to Adobe.
Internal Structure
A PDF file is 7-bit ASCII file, except for some binary streams (like images). It consists of a header, body (objects), cross-reference table, and a trailer. It supports compression, encryption, and digital signatures.
Advantages
- Universal compatibility: Looks the same on any device.
- Security: Supports password protection and digital signatures.
- Compactness: Can compress large documents into smaller files.
- Versatility: Can contain text, images, links, buttons, and even 3D models.
Disadvantages
- Difficult to edit: Not designed for content editing like a Word doc.
- Reflow issues: Fixed layout makes it hard to read on small screens (mobile phones) unless specifically optimized.
- Accessibility: Can be difficult for screen readers if not properly tagged.