HTML notes

HTML Introduction

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
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HTML Tags
HTML markup tags are usually called HTML tags
• HTML tags are keywords surrounded by angle brackets like
• HTML tags normally come in pairs like and
• 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.
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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:



My First Heading


My first paragraph




Example Explained
• The text between and describes the web page
• The text between and is the visible page content
• The text between
and
is displayed as a heading
• The text between

and
is displayed as a paragraph
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HTML Elements
HTML documents are defined by HTML elements.
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HTML Elements
An HTML element is everything from the start tag to the end tag:
Start tag * Element content End tag *

This is a paragraph

This is a link


* The start tag is often called the opening tag. The end tag is often called the closing tag.
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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
• Some HTML elements have empty content
• Empty elements are closed in the start tag
• Most HTML elements can have attributes
(You will learn about element attributes in the next chapter of this tutorial)
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Nested HTML Elements
Most HTML elements can be nested (can contain other HTML elements).
HTML documents consist of nested HTML elements.
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HTML Document Example


This is my first paragraph



The example above contains 3 HTML elements.
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Example Explained
The

element:

This is my first paragraph

The

element defines a paragraph in the HTML document
The element has a start tag

and an end tag

The element content is: This is my first paragraph
The element:

This is my first paragraph


The element defines the body of the HTML document
The element has a start tag and an end tag
The element content is another HTML element (a paragraph)
The element:



This is my first paragraph




The element defines the whole HTML document.
The element has a start tag and an end tag
The element content is another HTML element (the body)
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Don't Forget the End Tag
Most browsers will display HTML correctly even if you forget the end tag:

This is a paragraph

This is a paragraph
The example above will work in most browsers, but don't rely on it. Forgetting the end tag can produce unexpected results or errors.
Note: Future version of HTML will not allow you to skip end tags.
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Empty HTML Elements
HTML elements without content are called empty elements. Empty elements can be closed in the start tag.

is an empty element without a closing tag (it defines a line break).
In XHTML, XML, and future versions of HTML, all elements must be closed.
Adding a slash to the start tag, like
, is the proper way of closing empty elements, accepted by HTML, XHTML and XML.
Even if
works in all browsers, writing
instead is more future proof.
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HTML Tip: Use Lowercase Tags
HTML tags are not case sensitive:

means the same as

. Plenty of web sites use uppercase HTML tags in their pages.
HTML Attributes
Attributes provide additional information about HTML elements.
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HTML Attributes
• HTML elements can have attributes
• Attributes provide additional information about the element
• Attributes are always specified in the start tag
• Attributes come in name/value pairs like: name="value"
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Attribute Example
HTML links are defined with the tag. The link address is provided as an attribute:
Example
This is a link



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Always Quote Attribute Values
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='John "ShotGun" Nelson'
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HTML Tip: Use Lowercase Attributes
Attribute names and attribute values are case-insensitive.
Newer versions of (X)HTML will demand lowercase attributes.
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HTML Attributes Reference
A full list of legal attributes for each HTML element is listed in our:
Below is a list of some attributes that are standard for most HTML elements:

Attribute Value Description
class class_rule or style_rule The class of the element
id id_name A unique id for the element
style style_definition An inline style definition
title tooltip_text A text to display in a tool tip

HTML Headings

Headings are important in HTML documents.
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HTML Headings
Headings are defined with the
to
tags.
defines the largest heading.
defines the smallest heading.
Example
This is a heading

This is a heading

This is a heading




Note: Browsers automatically adds an empty line before and after headings.
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Headings Are Important
Use HTML headings for headings only. Don't use headings to make text BIG or bold.
Search engines use your headings to index the structure and content of your web pages.
Since users may skim your pages by its headings, it is important to use headings to show the document structure.
H1 headings should be used as main headings, followed by H2 headings, then less important H3 headings, and so on.
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HTML Rules (Lines)
The tag is used to create an horizontal rule (line).

Example

This is a paragraph


This is a paragraph


This is a paragraph




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HTML Comments
Comments can be inserted in the HTML code to make it more readable and understandable. Comments are ignored by the browser and are not displayed.
Comments are written like this:
Example




Note: There is an exclamation point after the opening bracket, but not before the closing bracket.
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HTML Tip - How to View HTML Source
Have you ever seen a Web page and wondered "Hey! How did they do that?"
To find out, click the VIEW option in your browser's toolbar and select SOURCE or PAGE SOURCE. This will open a window that shows you the HTML code of the page.
________________________________________HTML Tag Reference

Tag Description

Defines an HTML document

Defines the document's body
to

Defines header 1 to header 6

Defines a horizontal rule

Defines a comment
HTML Paragraphs
HTML documents are divided into paragraphs.
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HTML Paragraphs
Paragraphs are defined with the

tag.
Example

This is a paragraph

This is another paragraph




Note: Browsers automatically adds an empty line before and after paragraphs.
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Don't Forget the End Tag
Most browsers will display HTML correctly even if you forget the end tag:
Example

This is a paragraph

This is another paragraph



The example above will work in most browsers, but don't rely on it. Forgetting the end tag can produce unexpected results or errors.
Note: Future version of HTML will not allow you to skip end tags.
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HTML Line Breaks
Use the
tag if you want a line break (a new line) without starting a new paragraph:

Example

This is
a para
graph with line breaks




The
element is an empty HTML element. It has no end tag.
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or

In XHTML, XML, and future versions of HTML, HTML elements with no end tag (closing tag) are not allowed.
Even if
works in all browsers, writing
instead is more future proof.
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HTML Output - Useful Tips
You cannot be sure how HTML will be displayed. Large or small screens, and resized windows will create different results.
With HTML, you cannot change the output by adding extra spaces or extra lines in your HTML code.
The browser will remove extra spaces and extra lines when the page is displayed. Any number of lines count as one space, and any number of spaces count as one space.
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HTML Tag Reference
Tag Description


Defines a paragraph


Inserts a single line break





HTML Text Formatting
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HTML Text Formatting
This text is bold

This text is big

This text is italic

This is computer output

This is subscript and superscript



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HTML Formatting Tags
HTML uses tags like and for formatting output, like bold or italic text.
These HTML tags are called formatting tags.
Refer to the bottom of this page for a complete reference.
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HTML Styles
The style attribute is a new HTML attribute. It introduces CSS to HTML.
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Look! Styles and colors
This text is in Verdana and red
This text is in Times and blue
This text is 30 pixels high
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The HTML Style Attribute
The purpose of the style attribute is:
To provide a common way to style all HTML elements.
Styles was introduced with HTML 4, as the new and preferred way to style HTML elements. With HTML styles, styles can be added to HTML elements directly by using the style attribute, or indirectly by in separate style sheets (CSS files).
You can learn everything about styles and CSS in our CSS tutorial.
In our HTML tutorial we use the style attribute to introduce you to HTML styles.
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HTML Style Examples
style="background-color:yellow"
style="font-size:10px"
style="font-family:Times"
style="text-align:center"
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Deprecated Tags and Attributes
In HTML 4, some tags and attributes are defined as deprecated. Deprecated means that they will not be supported in future versions of HTML and XHTML.
The message is clear: Avoid the use of deprecated tags and attributes.
These tags and attributes should be avoided:
Tags Description