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Note for Internet and Web-Technologies - IWT by sagar prajapati

  • Internet and Web-Technologies - IWT
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Physical tags were invented to add style to HTML pages because style sheets were not around, though the original intention of HTML was to not have physical tags. Rather than use physical tags to style your HTML pages, you should use style sheets. HTML Elements Remember the HTML example from the previous page: <html> <head> <title>My First Webpage</title> </head> <body> This is my first homepage. <b>This text is bold</b> </body> </html> This is an HTML element: <b>This text is bold</b> The HTML element begins with a start tag: <b> The content of the HTML element is: This text is bold The HTML element ends with an end tag: </b> The purpose of the <b> tag is to define an HTML element that should be displayed as bold. This is also an HTML element: <body> This is my first homepage. <b>This text is bold</b> </body> This HTML element starts with the start tag <body>, and ends with the end tag </body>. The purpose of the <body> tag is to define the HTML element that contains the body of the HTML document. Nested Tags You may have noticed in the example above, the <body> tag also contains other tags, like the <b> tab. When you enclose an element in with multiple tags, the last tag opened should be the first tag closed. For example: <p><b><em>This is NOT the proper way to close nested tags.</p></em></b> <p><b><em>This is the proper way to close nested tags. </em></b></p> Note: It doesn't matter which tag is first, but they must be closed in the proper order. Why Use Lowercase Tags? You may notice we've used lowercase tags even though I said that HTML tags are not case sensitive. <B> means the same as <b>. The World Wide Web Consortium (W3C), the group responsible for developing web standards, recommends lowercase tags in their HTML 4 recommendation, and XHTML (the next generation HTML) requires lowercase tags. Tag Attributes Tags can have attributes. Attributes can provide additional information about the HTML elements on your page. The <tag> tells the browser to do something, while the attribute tells the browser how to do it. For instance, if we add the bgcolor attribute, we can tell the browser that the background color of your page should be blue, like this: <body bgcolor="blue">.

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This tag defines an HTML table: <table>. With an added border attribute, you can tell the browser that the table should have no borders: <table border="0">. Attributes always come in name/value pairs like this: name="value". Attributes are always added to the start tag of an HTML element and the value is surrounded by quotes. Quote Styles, "red" or 'red'? Attribute values should always be enclosed in quotes. Double style quotes are the most common, but single style quotes are also allowed. In some rare situations, like when the attribute value itself contains quotes, it is necessary to use single quotes: name='George "machine Gun" Kelly' Note: Some tags we will discuss are deprecated, meaning the World Wide Web Consortium (W3C) the governing body that sets HTML, XML, CSS, and other technical standards decided those tags and attributes are marked for deletion in future versions of HTML and XHTML. Browsers should continue to support deprecated tags and attributes, but eventually these tags are likely to become obsolete and so future support cannot be guaranteed. For a complete list of tags, visit W3C.org. Basic HTML Tags The most important tags in HTML are tags that define headings, paragraphs and line breaks. Basic HTML Tags Tag Description <html> Defines an HTML document <body> Defines the document's body <h1> to <h6> Defines header 1 to header 6 <p> Defines a paragraph <br> Inserts a single line break <hr> Defines a horizontal rule <!--> Defines a comment Headings Headings are defined with the <h1> to <h6> tags. <h1> defines the largest heading while <h6> defines the smallest. <h1>This is a heading</h1> <h2>This is a heading</h2> <h3>This is a heading</h3> <h4>This is a heading</h4> <h5>This is a heading</h5> <h6> This is a heading</h6> HTML automatically adds an extra blank line before and after a heading. A useful heading attribute is align.

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<h5 align="left">I can align headings </h5> <h5 align="center">This is a centered heading </h5> <h5 align="right">This is a heading aligned to the right </h5> Paragraphs Paragraphs are defined with the <p> tag. Think of a paragraph as a block of text. You can use the align attribute with a paragraph tag as well. <p align="left">This is a paragraph</p> <p align="center">this is another paragraph</p> Important: You must indicate paragraphs with <p> elements. A browser ignores any indentations or blank lines in the source text. Without <p> elements, the document becomes one large paragraph. HTML automatically adds an extra blank line before and after a paragraph. Line Breaks The <br> tag is used when you want to start a new line, but don't want to start a new paragraph. The <br> tag forces a line break wherever you place it. It is similar to single spacing in a document. This Code <p>This <br> is a para<br> graph with line breaks</p> Would Display This is a para graph with line breaks The <br> tag has no closing tag. Horizontal Rule The <hr> element is used for horizontal rules that act as dividers between sections, like this: The horizontal rule does not have a closing tag. It takes attributes such as align and width. For instance: This Code Would Display <hr width="50%" align="center"> Comments in HTML The comment tag is used to insert a comment in the HTML source code. A comment can be placed anywhere in the document and the browser will ignore everything inside the brackets. You can use comments to write notes to yourself, or write a helpful message to someone looking at your source code. This Code <p> This html comment would <!-- This is a comment --> be displayed like this.</p> Would Display This HTML comment would be displayed like this. Notice you don't see the text between the tags <!-- and -->. If you look at the source code, you would see the comment. To view the source code for this page, in your browser window, select View and then select Source.

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Note: You need an exclamation point after the opening bracket <!-- but not before the closing bracket -->. HTML automatically adds an extra blank line before and after some elements, like before and after a paragraph, and before and after a heading. If you want to insert blank lines into your document, use the <br> tag. Try It Out! Open your text editor and type the following text: <html> <head> <title>My First Webpage</title> </head> <body> <h1 align="center">My First Webpage</h1> <p>Welcome to my first web page. I am writing this page using a text editor and plain old html.</p> <p>By learning html, I'll be able to create web pages like a pro....<br> which I am of course.</p> </body> </html> Save the page as mypage2.html. Open the file in your Internet browser. To view how the page should look, visit this web page: http://profdevtrain.austincc.edu/html/mypage2.html Other HTML Tags As mentioned before, there are logical styles that describe what the text should be and physical styles which actually provide physical formatting. It is recommended to use the logical tags and use style sheets to style the text in those tags. Logical Tags Tag <abbr> <acronym> <address> <cite> <code> Physical Tags Description Defines an abbreviation Defines an acronym Defines an address element Defines a citation Defines computer code text <blockquote> Defines <del> Defines <dfn> Defines <em> Defines <ins> Defines <kbd> Defines <pre> Defines <q> Defines <samp> Defines <strong> Defines <var> Defines a long quotation text a definition term emphasized text inserted text keyboard text preformatted text a short quotation sample computer code strong text a variable Tag <b> Description Defines bold text <big> Defines big text <i> Defines italic text <small> Defines small text <sup> Defines superscripted text <sub> Defines subscripted text <tt> Defines teletype text <u> Deprecated. Use styles instead Character tags like <strong> and <em> produce the same physical display as <b> and <i> but are more uniformly supported across different browsers.

Lecture Notes