The PDF Standard
The vector-based and scalable Portable Document Format was first published by Adobe Systems in 1993, and it turned into an open standard through ISO 320001:2008 only two years ago (PDF 1.7). It is designed to be readable and printable in a platform-independent way, meaning that the hardware, operating system, and application software used to create the document must be irrelevant. It has also been a standard format for professional printing (PDF/X).
As you can imagine, this is particularly helpful for eliminating issues that arise because of missing fonts, misplaced page breaks, or file format difficulties, such as the incompatibilities between Word 2003 (.doc) and Word 2007 (.docx). In addition, the PDF format not only embeds all document content, but it also adds control elements to enable a clickable table of contents, preview thumbnails, or in-document forms. Finally, a PDF is protected, so the original content cannot be manipulated easily. PDF documents can be password-protected, and it is possible to prevent printing.
Viewing and printing a PDF requires the Adobe Acrobat Reader (click here for download), available for all popular operating systems and in 35 different languages. You may also use alternatives, such as Foxit, Ghostscript, or Okular.
There is no real size limit for PDF documents, not even with hundreds of thousands of pages in one file. Popular page formats include Letter and A4, but ever since Acrobat 7, it has also been possible to create pages in huge dimensions. Each and every element within a PDF document is stored as an object, which means that PDF documents with images, encoding, font information, comments, and form fields may easily hold thousands of objects.
PDF is based on three elements: a graphics model that is very similar to PostScript, a font management system to embed required fonts into the PDF, and structured storage to manage all objects, as well as compression.
The creation of a PDF document is either triggered through application integration (the PDF tool takes over from your source application, such as MS Office) or PDFs are converted through printing the document. The PDF creation tool installs a printer driver that allows one to make the desired settings and to save the PDF to your target location.