Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it. In 1991, Adobe Systems co-founder John Warnock outlined a system called "Camelot" that evolved into PDF. While Adobe Systems made the PDF specification available free of charge in 1993, PDF was a proprietary format, controlled by Adobe, until it was officially released as an open standard on July 1, 2008, and published by the International Organization for Standardization as ISO 32000-1:2008, at which time control of the specification passed to an ISO Committee of volunteer industry experts.
HTML stands for HyperText Markup Language ("markup language hypertext"), refers to the markup language for web development. It is a standard that serves as a reference for the development of websites in different versions, defines a basic structure and code (called HTML) to define the content of a website, such as text, images, and more. It is a standard by the W3C, an organization dedicated to the standardization of almost all web-related technologies, especially about their writing and interpretation. A web browser can read HTML files and compose them into visible or audible web pages. The browser does not display the HTML tags, but uses them to interpret the content of the page. HTML describes the structure of a semantic web site along with the signals for the presentation, so it is a markup language rather than a programming language.