What is HTML?

HTML (Hypertext Markup Language) is the standard markup language used for creating web pages and web applications. Alongside Cascading Style Sheets (CSS) and JavaScript (JS), it forms the triad of the World Wide Web (WWW). A web browser would typically receive HTML documents from either a web server or local storage. These documents are then rendered into multimedia web pages by the browser for viewing by a user. As such, these documents make up the structure of a web page semantically and originally, cues for the appearance of the document.

Through the use of HTML elements, a web page can consist of various different entities ranging from images to interactive web forms. This is accomplished by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes, and etc. These elements are identified by tags; angled brackets surrounding the keyword. For example, tags such as <img /> and <input /> are used to display content on the page while other tags such as <p>… <p> surrounded text but no tags are ever actually displayed by the browser as they're only used to interpret the page's contents. 

It should be noted that HTML can go a step further and allow developers to embed scripts into it such as JavaScript and Cascading Style Sheets to further manipulate and define how the content appears.  

History of HTML

For its first five years (1990-1995), HTML went through a number of revisions and  experienced a number of extensions, primarily hosted first at CERN, and then at the IETF. 

With the creation of the W3C, HTML's development changed venue again. A first abortive attempt at extending HTML in 1995 known as HTML 3.0 then made way to a more pragmatic approach known as HTML 3.2, which was completed in 1997. HTML4 followed, reaching completion in 1998. 

At this time, the W3C membership decided to stop evolving HTML and instead begin work on an XML-based equivalent, called XHTML. This effort started with a reformulation of HTML4 in XML, known as XHTML 1.0, which added no new features except the new serialization, and which was completed in 2000. After XHTML 1.0, the W3C's focus turned to making it easier for other working groups to extend XHTML, under the banner of XHTML Modularization. In parallel with this, the W3C also worked on a new language that was not compatible with the earlier HTML and XHTML languages, calling it XHTML2. 

Around the time that HTML's evolution was stopped in 1998, parts of the API for HTML developed by browser vendors were specified and published under the name DOM Level 1 (in 1998) and DOM Level 2 Core and DOM Level 2 HTML (starting in 2000 and culminating in 2003). These efforts then petered out, with some DOM Level 3 specifications published in 2004 but the working group being closed before all the Level 3 drafts were completed. 

In 2003, the publication of XForms, a technology which was positioned as the next generation of Web forms, sparked a renewed interest in evolving HTML itself, rather than finding replacements for it. This interest was borne from the realization that XML's deployment as a Web technology was limited to entirely new technologies (like RSS and later Atom), rather than as a replacement for existing deployed technologies (like HTML). 

A proof of concept to show that it was possible to extend HTML4's forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages, was the first result of this renewed interest. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software's copyright. 

The idea that HTML's evolution should be reopened was tested at a W3C workshop in 2004, where some of the principles that underlie the HTML5 work (described below), as well as the aforementioned early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web's evolution; the W3C staff and membership voted to continue developing XML-based replacements instead. 

Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort under the umbrella of a new venue called the WHATWG. A public mailing list was created, and the draft was moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors and to allow reuse of the specification. 

The WHATWG was based on several core principles, in particular, that technologies need to be backward compatible, that specifications and implementations need to match even if this means changing the specification rather than the implementations, and that specifications need to be detailed enough that implementations can achieve complete interoperability without reverse-engineering each other. 

The latter requirement in particular required that the scope of the HTML5 specification include what had previously been specified in three separate documents: HTML4, XHTML1, and DOM2 HTML. It also meant including significantly more detail than had previously been considered the norm. 

In 2006, the W3C indicated an interest to participate in the development of HTML5 after all, and in 2007 formed a working group chartered to work with the WHATWG on the development of the HTML5 specification. Apple, Mozilla, and Opera allowed the W3C to publish the specification under the W3C copyright while keeping a version with the less restrictive license on the WHATWG site. Since then, both groups have been working together. 

How Does HTML Work?

HTML stands for Hypertext Markup Language and is used to describe the visual appearance of a document to be displayed by an internet browser. HTML documents consist of document tags which act to directly describe the visual appearance of a web page or to provide a directive command such as inserting imagery or a link to another web page within a document. HTML documents are saved in text format and are designed to be viewed or edited on any operating system that is able to connect to the Internet. XHTML refers to the latest version(s) of the HTML definition that are designed to make use of the extensible markup language definition rules and syntax in order to permit web developers to continue to do advanced web page development. 

What Are the Required Parts of an HTML Page? 

HTML documents are defined by tags that consist of an opening and closing tag in order for the document to be considered “well-formed.” A closing tag will have the same name as an opening tag but will be preceded by the / symbol. All HTML documents must have an HTML and BODY tag in order to be displayed in a web browser. 

Other tags that are common to HTML pages include the document HEAD, TITLE, and P (paragraph) tags. For example :

The <HTML> tag in the example code declares the document to be type HTML to a web browser. The <HEAD> tag contains a <TITLE> tag that will be displayed in the top of a web browser and can also contain Javascript and other meta data information for the web page. The <BODY> tag contains the displayable information in the HTML document and includes a header tag <H2> declaration and defines a new paragraph tag <P>. Although an HTML page can be displayed without all tags having corresponding closing tags, it is not considered to be a well-formed document and may have display errors if all tags are not closed. 

Who Controls HTML Tag Definitions? 

The World Wide Web Consortium, or W3C, is an international community with participating member organizations who work opening to develop and implement Web standards. A common problem early in the use of the Internet was a lack of consistent standards for how to interpret and display web pages. This resulted in inconsistent quality experienced by the end user and increased expenditures by industry to program pages for multiple web browsers. The W3C HTML working group works with industry and academia in order to provide recommendations on the next versions for HTML (or XHTML) to be adopted as international standards and implemented by web browser companies.