Saturday, 1 February 2014

HTML Introduction



HTML Introduction

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>

What is HTML?

HTML is a language for describing web pages.
  • HTML stands for Hyper Text Markup Language
  • HTML is not a programming language, it is a markup language
  • A markup language is a set of markup tags
  • HTML uses markup tags to describe web pages

HTML Tags

HTML markup tags are usually called HTML tags
  • HTML tags are keywords surrounded by angle brackets like <html>
  • HTML tags normally come in pairs like <b> and </b>
  • The first tag in a pair is the start tag, the second tag is the end tag
  • Start and end tags are also called opening tags and closing tags

HTML Documents = Web Pages

  • HTML documents describe web pages
  • HTML documents contain HTML tags and plain text
  • HTML documents are also called web pages
The purpose of a web browser (like Internet Explorer or Firefox) is to read HTML documents and display them as web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page:
<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>

Example Explained

  • The DOCTYPE declaration defines the document type (HTML 5)
  • The text between <html> and </html> describes the web page
  • The text between <body> and </body> is the visible page content
  • The text between <h1> and </h1> is displayed as a heading
  • The text between <p> and </p> is displayed as a paragraph

HTML - Getting Started

What You Need

You don't need any tools to learn HTML
  • You don't need an HTML editor
  • You don't need a web server
  • You don't need a web site

HTML Elements

HTML documents are defined by HTML elements.

HTML Elements

An HTML element is everything from the start tag to the end tag:
Start tag *
Element content
End tag *
<p>
     This is a paragraph
          </p>
<a href="default.htm">
   This is a link
          </a>
<br />


* The start tag is often called the opening tag. The end tag is often called the closing tag.

HTML Element Syntax

  • An HTML element starts with a start tag / opening tag
  • An HTML element ends with an end tag / closing tag
  • The element content is everything between the start and the end tag
  • Empty elements are
  • Some HTML elements have empty content
  • closed in the start tag
  • Most HTML elements can have attributes
You will learn about attributes in next.

Nested HTML Elements

Most HTML elements can be nested (can contain other HTML elements).
HTML documents consist of nested HTML elements.

HTML Document Example

<!DOCTYPE html>
<html>

<body>
<p>This is my first paragraph.</p>
</body>

</html>
The example above contains 3 HTML elements.

HTML Example Explained

The <p> element:
<p>This is my first paragraph.</p>
The <p> element defines a paragraph in the HTML document.
The element has a start tag <p> and an end tag </p>.
The element content is: This is my first paragraph.
The <body> element:
<body>
<p>This is my first paragraph.</p>
</body>
The <body> element defines the body of the HTML document.
The element has a start tag <body> and an end tag </body>.
The element content is another HTML element (a p element).
The <html> element:
<html>

<body>
<p>This is my first paragraph.</p>
</body>

</html>
The <html> element defines the whole HTML document.
The element has a start tag <html> and an end tag </html>.
The element content is another HTML element (the body element).

Don't Forget the End Tag

Some HTML elements might display correctly even if you forget the end tag:
<p>This is a paragraph
<p>This is a paragraph
The example above works in most browsers, because the closing tag is considered optional.
Never rely on this. Many HTML elements will produce unexpected results and/or errors if you forget the end tag .

Empty HTML Elements

HTML elements with no content are called empty elements.
<br> is an empty element without a closing tag (the <br> tag defines a line break).
Tip: In XHTML, all elements must be closed. Adding a slash inside the start tag, like <br />, is the proper way of closing empty elements in XHTML (and XML).

HTML Tip: Use Lowercase Tags

HTML tags are not case sensitive: <P> means the same as <p>. Many web sites use uppercase HTML tags.
World Wide Web Consortium (W3C) recommends lowercase in HTML 4, and demands lowercase tags in XHTML.


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