What Does PDF Stand For?

If you’ve ever downloaded a document or form from the Web, it was probably in PDF format. It is the most common file type used today.

Adobe created the PDF format to allow people to present and exchange documents reliably, regardless of hardware, software, or operating systems. PDF can contain text, graphics, links, buttons, form fields, and even video.

Portable Document Format

PDF is a universal file format that is able to be viewed and printed with the same quality regardless of the software, hardware or operating system used to view it. This makes it the ideal file format for sharing statistical reports, invoices or contracts that must be viewed and edited by users across multiple platforms.

Although initially proprietary, Adobe’s PDF file format was made an open standard in 2008 and is now maintained by ISO as part of its 32000 series. The current ISO specification for full function PDF (sometimes referred to as PDF 1.7) still includes some proprietary technologies defined only by Adobe, but these are being phased out in favor of an entirely new set of standards.

The free software project GNU PDF, which maintains the poplar library for implementing PDF in applications, is an example of an open source, free and compatible implementation of the ISO PDF standard. This is one of the many reasons why PDFs are so widely adopted around the world.

Form Fields

Online form builders enable you to create contact forms or registration forms to gather information from your visitors. They also support different form field types that allow you to collect the most relevant data.

For example, the select> tag can be used to create a dropdown box that allows users to select from predefined options. Likewise, the text area> tag can be used to capture multiline text input. These forms can then be validated and processed with JavaScript.

Moreover, the PDF specification includes a number of other features that go beyond flat text and graphics. These include logical grouping elements for annotations and form fields, layers, rich media (including video content) and three-dimensional objects using U3D or PRC, and metadata.

For instance, the file format supports security. It supports both a user password that encrypts the PDF and an owner password that restricts some operations, such as modifying, printing or copying text and graphics out of the document.

Graphics

Graphics can be anything that is visual – such as illustrations, pictures, graphs and charts. They are often used in a PDF document to convey information or make it more interesting and understandable. They can also be animated, which is useful for explaining certain concepts like human anatomy.

PDF graphics may include font objects which describe the characteristics of a digital typeface or include an embedded font file. PDF supports embedding fonts based on widely-used standard digital font formats, including Type 1 (and its compressed variant CFF), TrueType and, beginning with PDF 1.6, OpenType.

PDF documents can contain a variety of display settings in a Page Display Layout object, including zoom level and viewer preferences. The free Adobe Reader program automatically sets these options when it opens the document. A PDF can also be tagged to include text equivalents, captions and audio descriptions. These can be accessed by leading screen readers, such as JAWS, Window-Eyes and Kurzweil 1000 and 3000.

Text

The development of PDF was prompted by the need for documents to be displayed in an electronic form that is independent of hardware, software and operating systems. This file format is the world’s most widely used online and it allows for the use of form fields, multimedia, business logic, an electronic signature and a number of other features that make PDFs a vital tool for business and in the world of marketing.

Text in PDF is represented by text elements in page content streams. Each text element defines an area that should contain characters in a given font. The characters are specified by an encoding (which is the set of character codes that map to glyphs in a font). The text stream can either contain a predefined encoding like WinAnsi or MacRoman or it can reference an embedded font that uses one of these encodings.

PDF files may also be tagged for accessibility, which means that they can contain tags, text equivalents, captions and audio descriptions. Leading screen readers such as JAWS, Window-Eyes and Hal can read tagged PDFs.

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