Publishing HTML with HTTP

Publishing HTML with HTTP

The World Wide Web is primarily composed of HTML documents transmitted from a web server to a web browser using the Hypertext Transfer Protocol (HTTP). However, HTTP can be used to serve images, sound and other content in addition to HTML. To allow the web browser to know how to handle the document it received, an indication of the file format of the document must be transmitted along with the document. This vital metadata includes the MIME type (text/html for HTML 4.01 and earlier, application/xhtml+xml for XHTML 1.0 and later) and the character encoding (see Character encodings in HTML).

In modern browsers, the MIME type that is sent with the HTML document affects how the document is interpreted. A document sent with an XHTML MIME type, or served as application/xhtml+xml, is expected to be well-formed XML and a syntax error may cause the browser to fail to render the document. The same document sent with a HTML MIME type, or served as text/html, might get displayed since web browsers are more lenient with HTML. However, XHTML parsed this way is not considered either proper XHTML nor HTML, but so-called tag soup.

If the MIME type is not recognized as HTML, the web browser should not attempt to render the document as HTML, even if the document is prefaced with a correct Document Type Declaration. Nevertheless, some web browsers do examine the contents or URL of the document and attempt to infer the file type, despite this being forbidden by the HTTP 1.1 specification.

HTML e-mail

Main article: HTML e-mail

Most graphical e-mail clients allow the use of a subset of HTML (often ill-defined) to provide formatting and semantic markup capabilities not available with plain text, like emphasized text, block quotations for replies, and diagrams or mathematical formulas that couldn't easily be described otherwise. Many of these clients include both a GUI editor for composing HTML e-mails and a rendering engine for displaying received HTML e-mails. Use of HTML in e-mail is controversial due to compatibility issues, because it can be used in phishing/privacy attacks, because it can confuse spam filters, and because the message size is larger than plain text.

Current flavors of HTML

Since its inception HTML and its associated protocols gained acceptance relatively quickly. However, no clear standards existed in the early years of the language. Though its creators originally conceived of HTML as a semantic language devoid of presentation details, practical uses pushed many presentational elements and attributes into the language: driven largely by the various browser vendors. The latest standards surrounding HTML reflect efforts to overcome the sometimes chaotic development of the language and to create a rational foundation to build both meaningful and well-presented documents. To return HTML to its role as a semantic language, the W3C has developed style languages such as CSS and XSL to shoulder the burden of presentation. In conjunction the HTML specification has slowly reined in the presentational elements within the specification.

There are two axes differentiating various flavors of HTML as currently specified: SGML-based HTML versus XML-based HTML (referred to as XHTML) on the one axis and strict versus transitional (loose) versus frameset on the other axis.

Refference :

1. http://en.wikipedia.org/wiki/HTML