HTML stands for HyperText Markup Language (Hypertext Markup Language), is the predominant markup language for building Web pages. It is used to describe the structure and content in text form, as well as to complement the text with objects such as pictures. HTML is written in the form of “labels”, surrounded by angle brackets (<,>). HTML also can describe, to a certain extent, the appearance of a document, and may include a script (eg Javascript), which can affect the behavior of other web browsers and HTML processors.
HTML is also used to refer to the contents of the kind of mime text / html or even more widely as a generic term for HTML, either fell from XML (such as XHTML 1.0 or later) or in the form descend directly from SGML (as HTML 4.01 and above).
By convention, files HTML format using the extension. Htm or. Html.
The first description of HTML publicly available was a paper called HTML Tags (HTML tags), first mentioned on the Internet by Tim Berners-Lee in 1991. [1] [2] describes 22 elements comprising the initial design and relatively simple HTML . Thirteen of these elements still exist in HTML 4. [3]
Berners-Lee considered an extension of HTML SGML, but was not formally recognized as such until the publication of mid-1993 by the IETF, an initial proposal for a specification of HTML: Hypertext Markup Language sketch of Berners-Lee and Dan Connolly, which included a Document Type Definition SGML to define the grammar. [4] The sketch expired after six months, but was notable for its recognition of the label’s own Mosaic browser used to insert images unchanged line , Reflecting the philosophy of IETF standards based on prototypes with success. [5] Similarly, the sketch competitor Dave Raggett + HTML (Hypertext Markup Format) (hypertext mark-format) of late 1993, suggesting, standardize features already implemented such as tables.
The elements are the basic structure of HTML. The elements have two basic properties: attributes and content. Each attribute content and has certain restrictions to be considered valid document to HTML. One element usually have a label home (eg <nombre-de-elemento>) and a closing tag (eg </ name-of-item>). The item’s attributes are contained in the label start and the content is located between the two labels (eg <nombre-de-elemento atributo=”valor”> content </ name-of-item>). Some elements, such as <br> have no content or lead a closing tag. Below are listed several types of tagging elements used in HTML.
Overall structure of a line of code in the language of HTML tags
Overall structure of a line of code in the language of HTML tags
The sharp structural describes the purpose of the text. For example, <h2> Golf </ h2> establishes a “Golf” heading as a second-tier, which will display in a browser in a similar way to the title “Marked HTML” at the beginning of this section. The sharp structural does not define how will the element, but most web browsers have standardized format of the elements. A specific format can be applied to text with cascading style sheets.
The sharp Presentational describes the appearance of text, regardless of their function. For example, <b> bold </ b> indicates that visual web browsers must show the text in bold, but does not indicate what to do web browsers that show the contents of another way (for example, those who read the text in aloud). In the case of <b> bold </ b> and <i> italic </ i>, there are elements that are in the same way but have a more semantic nature: <strong> strong emphasis </ strong> and <em > emphasis </ em>. It’s easy to see how a screen reader should interpret these two elements. However, are equivalent to their respective presentational elements: a screen reader should not say stronger the name of a book, although it is in italics on a screen. Most of marking Presentational has been discarded with HTML 4.0, for cascading style sheets.
ost of the attributes of an element are name-value pairs, separated by an equal sign “=” and written on the label of the start of an item, after the name of it. The value can be surrounded by double quotes or simple, although certain types of securities can be no quotes in HTML (but not in XHTML). [7] [8] In any case, let the values without quotation marks is considered unsafe. [ 9] In contrast to peer-name element, there are some attributes that affect the element simply by their presence [10] (as the attribute ismap for the img element
* <html>: Defines the start of the HTML document, tells the browser that what comes out below should be interpreted as HTML.
* <head>: Defines the headwaters of the HTML document, this header normally contains information on the document which is not shown directly to the user. Such as the title of the browser window. Within the header <head> we find:
An example of HTML code with syntax highlighting
An example of HTML code with syntax highlighting
* <title>: Defines the title page. Usually, the title appears in the title bar above the window
* <link>: To link the site to style sheets or icons For example: <link rel=”stylesheet” href=”/style.css” type=”text/css”>
* <style>: To move the style of the page, either using CSS, JavaScript or other similar languages. There is no need to inject whether to link to an external file using the label <link>
* <body>: Defining the content or main body of the document. This part of html document that appears in the browser; within this element can be defined properties common to all the site, as background color and margins. Within the body <body> we can find many labels. The following are some as an example:
* <h1>, <h2>, <h3>, <h4>, <h5>, <h6>: Headers or titles of the document with a different significance.
* <table>: Defines a table
* <tr>: Row of a table
* <td>: Cell data from a table
* <a>: Hyperlink or link, inside or outside the site. You must define the parameters in passing through the href attribute. For example: <a href=”http://www.wikipedia.org”> Wikipedia </ a> is represented as Wikipedia)
* <div>: Area of the page
* <img>: Image. Requires the src attribute, which indicates the path that lies in the image. For example: <img src=”./imagenes/mifoto.jpg” />
* <li> <ol> <ul>: Labels lists.
* <b>: Text in bold (Tag discarded. It is recommended to use the label <strong>)
* <i>: Text in italics
* <u>: Underlined text
* Most labels must be closed as open, but with a slash (“/”) as shown in the following examples:
* <table> <tr> <td> Content of a cell </ td> </ tr> </ table>
* <script> Code a script composed at </ script>
The HTML can be created and edited with any basic text editor such as Gedit on Linux, Windows Notepad or any other editor that supports plain text like GNU Emacs, Microsoft Wordpad, Textpad, Vim, Note + + pad, etc..
There are also other programs for the realization of Web sites or editing HTML code, such as Microsoft FrontPage, which has a basic format similar to other Office programs. There is also the famous Macromedia Software (acquired by Adobe) called Dreamweaver, being one of the most widely used in the field of web design and programming. These programs are known as WYSIWYG editors or What You See Is What You Get (in Spanish: “what you see is what you get”). This means that publishers are in which is the result of what is being edited in real time as the document as it develops. However, this does not mean a different way to make websites, but a somewhat simpler for these programmes, besides having the option of working with the preview, HTML has its own section which will generate wide code as you work.
Combining these two methods is very interesting, because somehow help each other. For example, if everything is published in HTML and suddenly forget any code or label, I simply say to the editor or visual WYSIWYG and there is continued publishing, or vice versa, since there are cases in which leaves faster and easier to write directly some feature of the code we want to accede to the site, to find the option in the program itself.
There is another type of HTML editors called WYSIWYM (What you see is what you mean) that give more importance to the content and meaning to the visual appearance. Among the objectives that have these editors is the separation of content and presentation, crucial in designing Web.
HTML uses tags or markings, which consist of brief instructions from the beginning and end, by which determines the way it should appear in your browser the text, as well as images and other elements on the computer screen.
Any label is identified because he is locked up among the signs that smaller and larger than (<>), and some have attributes that can take some courage. In general labels apply two special forms:
* To be open and close, such as: <b> bold </ b> would be in your web browser as bold.
* There can be opened and closed, as <hr> that would be in your web browser as a horizontal line.
* Other that can be opened and closed like <p>.
* The labels are basic or minimum:
Selecting the option View source in the browser, you can actually see the information they’re getting and how it is interpreted. For example: in Internet Explorer or Firefox, you just have to pull down the View menu and then choose Source Code. This will open the text editor configured as default in the system with the source code for the page you’re looking at that time in the browser. Another fastest way is to click the right mouse button anywhere in the area where the browser displays the Web page and choose View source.
For there is a Firefox browser plug FireBug, a debugger that allows among other things display the HTML of the page you are viewing in a dynamic way, and even emphasizes that the piece of code by the mouse is happening at every moment, what is a very useful tool for learning various concepts of this language. The plug can be obtained at: http://www.getfirebug.com/
In 1989 there were two techniques that allow linking electronic documents, on the one hand hyperlinks (links) and secondly a powerful language labels called SGML. By then an operator familiar with both options, Tim Berners-Lee nuclear physicist of the European Centre for Nuclear Research provides information to the press that he was working on a system that will allow access files online, working on computer networks or electronic machines based on the TCP / IP protocol.
In early 1990, Tim Berners-Lee finally defines HTML as a subset of SGML known and creates something even more valuable, the World Wide Web. In 1991, Tim Berners-Lee created the first browser that would work in HTML text mode and for UNIX.
Work to create a successor to HTML called HTML +, began in late 1993. HTML + was designed originally to be a superset of HTML allowed to evolve gradually from the previous HTML format. The first formal specification of HTML + was given, hence, the version number 2 to distinguish it from previous proposals unofficial. Work on HTML + continued, but never became a standard, despite being based closer to formally compositional aspect of the current specifications.
The draft standard HTML 3.0 was proposed by the newly formed W3C in March 1995. It introduced many new capabilities, such as facilities for creating tables, making the text fluyese about the figures and show complex mathematical elements. Although it was designed to be compatible with HTML 2.0, was too complex to be implemented with the technology of the time, and when the draft standard expired in September 1995, was abandoned due to lack of support from manufacturers web browsers. The HTML 3.1 was never formally proposed, and was following standard HTML 3.2, leaving most of the new features of HTML 3.0 and, in return, took many items originally developed by Mosaic and Netscape Web browsers. The possibility of working with mathematical formulas that had been proposed in HTML 3.0 happened to be integrated into a different standard called MathML.
The HTML 4.0 also adopted many specific elements developed initially for a particular web browser, but at the same time began to clean up the HTML noting some of them as’ disapproved ‘.
The design HTML apart from complying with the specifications own language must respect the criteria of web accessibility, following guidelines or regulations and laws in force in countries where governing that concept. It is available and developed by the W3C through the Content Accessibility Guidelines 1.0 Web WCAG, although many countries have their own specifications such as Spain with the UNE 139803.
