PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created. A PDF file can be any length, contain any number of fonts and images and is designed to enable the creation and transfer of printer-ready output.
Each PDF file encapsulates a complete description of a 2D document (and, with the advent of Acrobat 3D, embedded 3D documents) that includes the text, fonts, images and 2D vector graphics that compose the document. They do not encode information that is specific to the application software, hardware, or operating system used to create or view the document.
Web pages are predominately marked up in HTML, these are then displayed through browsers such as Safari, Internet Explorer or Mozilla Firefox. It provides a means to describe the structure of text-based information in a document by denoting certain text as headings, paragraphs, links etc and to supplement that text with interactive forms, embedded images, and other objects. HTML source code is used by the Web browser and typically not seen by the user. The raw HTML can be viewed by choosing View Source from the Web browsers view menu or by opening the HTML file in a text editor.
Any Web Browser (e.g. Internet Explorer, Safari, Firefox, Google Chrome)