# HTML

## Contents

HTML stands for Hypertext Markup Language and is used to structure textual content of a web document. Not only is the content marked up, but also meta-information describing this content. HTML pages are usually stored in the root directory of the server.

## How it was created

In the digital age, users find it hard to find their way on websites and to keep track of page structures. Therefore, an encoding scheme is meant to make it possible to distinguish electronic documents. HTML was developed as a standard for the markup of web documents in the early 1990s. Initially, only simple functions such as syntax highlighting, setting of headers and links were possible. Over time, the W3C continued to further develop the markup language.

## Structure

Hypertext markup language is easy to edit and resembles an interpreter language. HTML code can be written with any text editor, and has no special requirements in its creation. A characteristic of HTML is the use of tags. Tags are defined elements which are standardized. A hierarchical structure is obtained through these elements.

A typical HTML structure is divided into head tags and body tags. A general HTML document construct looks like this:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<title> Title of a web document </title>
<body>


When creating the HTML code, it should be ensured that all integrated scripts can be loaded by the browser. Errors or bugs may adversely affect search engine optimization.

Meta information of a page which is not displayed in the browser is defined in the head (or HTML head). It contains important meta tags that are relevant for search engine crawlers (for example, the description tag). In order for the browser to be able to read the metadata contained in the HTML head and correctly run it with the right applications, much of this data can be defined with MIME.

### HTML body

The body (or HTML body) contains the actual content that is visually displayed by a browser as well as the CSS of a document, media content, text highlighting, and headers.

## Syntax

Correct syntax is essential when working with HTML. Tags exist in pairs, with a start tag example <head> and an end tag example </head>. The definition is defined by default in the document type definition (DTD). This syntax can be automatically checked for errors in the document through an HTML validator.

HTML continues to evolve because it is an open standard markup language. The use of CSS - cascading style sheets, Java Server Pages, XML - extended markup language or AJAX technology within the markup language are quite common.

### DHTML

DHTML (also known as DOM scripting) is dynamic HTML. It is a collective term for different variants in web design that change based on user input. The word “dynamic” which is used as part of the term denotes the fact that changes can occur even based on repeated retrieval of a website.

Examples of DHTML:

• Text highlighting
• Moving content of a website by the user
• Automatic completion of form fields based on previous entries

### Method

To implement DHTML functions, the document is generally drafted in HTML. Also, a client-side scripting language such as JavaScript is utilized. Additionally, the HTML document must be expanded and DOM (Document Object Model) is commonly used for that purpose. XMLHttpRequest is another necessary component so that data can be exchanged between browser and server and it provides a suitable data format for structured data, such as XML.

### CHTML

CHTML is an HTML standard for mobile devices. Compact HTML has been specially developed by wireless providers for this purpose. This markup language is characterized by the reduction of page content. JPEG images, tables or frames get removed, so that websites can be displayed on mobile phones with a small amount of memory. CHTML hardly differs from HTML. Existing websites can therefore quite easily be rewritten into CHTML.

Today only a few websites are programmed that way. Instead, web designers use responsive designs or other strategies to optimize websites for mobile devices.

### XTHML

XHTML is an extension of HTML. Images, text or hyperlinks can be marked up additionally with meta elements. For a long time, XHTML was considered the successor of the HTML standard. But it is likely that HTML5 will instead replace the previous standard since it offers even more options to mark up content.