Search engine

Transcript Search engine

WEB ENGINEERING AND
APPLICATIONS
ITC 311
REEM ALMOTIRI
Information Technology Department
Majmaah University
Lecture 7
The HTML meta Element
• Metadata is information about data. Metadata will not be
displayed on the page.
• The metadata can be used by browsers (how to display content
or reload page), search engines (keywords), or other web
services.
The <meta> tag
provides metadata about the HTML document.
Meta elements are typically used to specify page description,
keywords, author of the document, last modified, and other
metadata.
Search services
Originally there were two kinds of search services on the Web:
"Search engine" and “Search directory"
Search engine
Google and AltaVista are all forms of search engines.
These search engines write programs known as robots,
crawlers and/or spiders that have the following
functions:
(1) to locate Web pages,
(2) to read the contents of the Web pages
(3) report its findings back to the search engine's indices
or databases.
Many search engines update their index either on a bimonthly or monthly basis.
Search Directory
Yahoo!, Open Directory Project (dmoz.org), Gipsy are
forms of Web directories. These directories use human
editors to review sites that are submitted for submission to
the directory. Directories, unlike search engines, use a
hierarchical tree structure to organize their database.
Another common distinction is that a directory tends to
list Web sites (root directory of a site or homepage)
whereas a search engine will list Web pages (individual
pages of a Web site).
The HTML meta attributes
Some search engines will use the name and content attributes of
the meta element to index your pages.
Example 1 - Define keywords for search engines:
<meta name="keywords" content="HTML, CSS, XML,
XHTML, JavaScript" />
Example 2 - Define a description of your web page:
<meta name="description" content="Free Web tutorials on
HTML and CSS" />
Example 3 - Define the last revision of your page:
<meta name="revised" content="Hege Refsnes, 23/10/2011" />
Example 4 - Refresh document every 30 seconds:
<meta http-equiv="refresh" content="30" />
Example
Describe metadata within an HTML document:
<head>
<meta name="description" content="Free Web tutorials" />
<meta name="keywords" content="HTML,CSS,XML,JavaScript" />
<meta name="author" content="Hege Refsnes" />
<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
</head>
profile attribute
The URL in the profile attribute points to a document containing
information regarding metadata.
<head profile=http://www.yoursite.com/myprofile.txt >
Attribute
Value
Description
http-equiv
content-type
content-style-type
expires
set-cookie
others
Provides an HTTP header for the
information/value of the content attribute
name
author
description
keywords
generator
revised
others
Provides a name for the information in the
content attribute
Value
Description
author
Defines the author of the document.
Example:
<meta name="author" content="Hege Refsnes" />
copyright
Defines copyright information of the document.
Example:
<meta name="copyright" content="2011© W3Schools.com" />
description
Search engines can pick up this description to show with the results of searches.
Example:
<meta name="description" content="Free web tutorials" />
distribution
Declares whether the document is available to the web or on an intranet.
Example:
<meta name="distribution" content="web" />
expires
Specifies the date and time when the page expires.
Example:
<meta name="expires" content="Fri, 10 Jun 2011 12:00:00 GMT" />
keywords
Informs search engines what your site is about.
Example:
<meta name="keywords" content="HTML, HTML DOM, JavaScript" />
owner
Defines the owner of the page or site
refresh
The document will display for a specified amount of time before refreshing or
switch to a new URL.
Example:
<meta name="refresh" content="10" />
<meta name="refresh" content="10;URL=http://www.w3schools.com" />
Value
Description
contentlanguage
Specifies the natural language(s) of the document (used by search engines
to categorize pages by language).
Example:
<meta http-equiv="content-language" content="en-US" />
content-type
Specifies the character set for the contents of the document.
Example:
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
date
Specifies the date and time when the page was created.
Example:
<meta http-equiv="date" content="Wed, 16 Feb 2011 22:34:13 GMT" />
last-modified
Specifies the last modification date.
Example:
<meta http-equiv="last-modified" content="Mon, 03 Jan 2011 17:45:57
GMT" />
location
Redirects the visitor to another location.
Example:
<meta http-equiv="location" content="URL=http://www.w3schools.com" />