EITC/WD/HCF HTML and CSS Fundamentals

The Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. The markup language is for annotating a document in a way that is syntactically distinguishable from the text,so that when the document is processed for display, the markup language is not shown, and is only used to format the text properly. The markup term evolved from the “marking up” of paper manuscripts (in a revision process by editors), traditionally written with other color on authors’ manuscripts. Such markup typically includes both content corrections (such as spelling, punctuation, or movement of content), and also typographic instructions, such as to make a heading larger or boldface. In digital media, the colored markup instruction (text) was replaced by tags which indicate what the parts of the document are, rather than details of how they might be shown on some display. This lets authors avoid formatting every instance of the same kind of thing redundantly and possibly inconsistently. It also avoids the specification of fonts and dimensions which may not apply to many users (such as those with different-size displays, impaired vision and screen-reading software). The HTML is a standard markup language used in WWW. It can be assisted by technologies such as Cascading Style Sheets (CSS, for applying styling of the document) and scripting languages such as JavaScript (enabling dynamic logic on the side of the web browser). Web browsers receive HTML documents from a web server or from local storage and render the documents into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for the appearance of the document. HTML elements are the building blocks of HTML pages. With HTML constructs, images and other objects such as interactive forms may be embedded into the rendered page. HTML provides means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. HTML elements are delineated by tags, written using angle brackets. Tags such as <img /> and <input /> directly introduce content into the page. Other tags such as <p> surround and provide information about document text and may include other tags as sub-elements. Browsers do not display the HTML tags, but use them to interpret the content of the page. HTML can embed programs written in a scripting language such as JavaScript, which affects the behavior and content of web pages dynamically.

The Cascading Style Sheets (CSS) is a style sheet computer language used for describing the presentation of a document written in a markup language such as HTML. One important feature of structured documents is that the content can be reused in many contexts and presented in various ways. Different style sheets can be attached to the logical structure to produce different presentations. CSS is a cornerstone technology of the World Wide Web, alongside HTML and JavaScript. Inclusion of CSS defines the look and layout of the content of web sites. The World Wide Web Consortium (W3C), former maintainer of the HTML and current maintainer of the CSS standards, has encouraged the use of CSS over explicit presentational HTML since 1997. CSS is designed to enable separation of presentation and content, including layout, colors, and fonts, thus improving the content accessibility, providing more flexibility and control in the specification of presentation characteristics, enabling multiple web pages to share formatting by specifying the relevant CSS in separate .css files which reduces complexity and repetition in the structural content as well as enabling the .css files to be cached to improve the page loads speed between the pages that share the file and its formatting. Separation of formatting and content also makes it feasible to present the same markup page in different styles for different rendering methods, such as on-screen, in print, by voice (via speech-based browser or screen reader), and on Braille-based tactile devices. CSS also has rules for alternate formatting if the content is accessed on a mobile devices. The CSS name, ‘cascading’ comes from the specified priority scheme to determine which style rule applies if more than one rule matches a particular element. In addition to HTML, other markup languages support the use of CSS including XHTML, plain XML, SVG, and XUL.