Globale linker
Book 1
- Chapter 1
- Chapter 2
- Chapter 3
- Chapter 4
- Chapter 5
- Chapter 6
- Chapter 7
- Chapter 8
- Chapter 9
- Chapter 10
- Chapter 11
- Chapter 12
- Chapter 13
- Chapter 14
- Chapter 15
- Chapter 16/17
- Chapter 18/19
- Chapter 20
- Chapter 21
- Chapter 22/23
Book 2
Ch.14 Metadata
The DTD
The Document Type Definition tag precedes the opening <html> tag. Every conforming HTML document must start with the <!doctype> declaration, which is necessary to distinguish the version of HTML in use from other versions of HTML. This requirement is clearly stated in the HTML 3.2 standard. With three HTML 4.01 recommendations it is even more important to define which standard you are using. For example:
<!DOCTYPE HTML PUBLIC"-//W3C/DTD HTML 4.0 Transitional //EN">
The <title> is mandatory in HTML 3.2 and later version documents. If you omit the title, your document will not conform to the HTML 3.2 specification.
Metadata can be defined as data about data. It is data that embraces and describes a larger body of data. The metadata tag describes the content of a web page.
Meta-information consists of general information about the web page content that should be available, but not necessarily displayed for the user. This includes:
- Expiration date
- Author name
- Keywords to be used by some search engines
- A description to specify a synopsis of the page in some search engines
The <meta> tag requires the «content» attribute and either the «name» or the «http-equiv» attribute. The «http-equiv» and the «name» attributes define the general information you are creating or changing in the document and the «content» attribute defines the value of the general information.
<meta http-equiv>
<meta http-equiv> tags are equivalent to HTTP headers (headers that gives the web browser information useful for displaying the page). They can be used to control the actions of web browsers and further refine the information provided by the actual default headers. When using
<meta http-equiv> content can the values of:
- Expires
Defines a date when the file will be considered expired in cache.
<meta http-equiv="expires" content="Fri, 20 Nov 1998 08:00:00 GMT"> - Pragma
Controls the page cache to the browser folder
<meta http-equiv="pragma" content="no-cache">
- Refresh
Loads the page after the specified number of seconds, then takes the user to the specified URL
<meta http-equiv="refresh" content="8,URL=http://newpage.com" - Set-cookie
Creates a cookie to collect information
<meta http-equiv="set-cookie" content="cookievalue=xxx;expires=Friday,20-Nov-98 8:00:00 GMT"> - Window-target
Changes the default location where hyperlinks open
<meta http-equiv="window-target" content="main"> - Content-type
Causes the browser to load the appropriate charset before displaying the page.
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> - Content-Language
May be used to declare the natural language of the document. May be used by robots to categorize by language.
<meta http-equiv="Content-Language" content="en">
<Meta name >
<META NAME> is used for information types that do not correspond to HTTP headers. Name can hold the value of for example:
- Keywords
Keywords used by search engines to index your document in addition to words from the title and document body. Typically used for synonyms and alternates of title words.
<meta name="keywords" content="oranges, lemons, limes"> - Description
A short, plain language description of the document. Used by search engines to describe your document. Particularly important if your document has very little text, is a frameset, or has extensive scripts at the top.
<meta name="description" content="Citrus fruit wholesaler."> - Robots
Controls Web robots on a per-page basis.
<meta name="robots" content="noindex,follow"> - Author
Typically the unqualified author's name.
<meta name="author" content="Jens Morten Frøhoel"> - Copyright
A copyright statement.
<meta name="copyright" content="Copyright 2001 To the point Webdesign">
For more information about metadata see this metadata dictionary or you can generate metadata with the Dublin Core Metadata Template
Meta tags and search engines
Some search engines will search for values specified by the content attribute of <meta>-tags that have the value of the «name» attribute set to «keywords». Do not use keywords excessively.
When the <meta> tag «name» attribute specifies the «description» value, the «content» attribute value will appear as a short description in some search engine results. Keep this description breef: no more than 25 words.
There are two types of «search engines»:
- Search engines.
Uses an automated process to discover new web pages. This process, sometimes called a «robot» or a «spider», crawls around the web following hyperlinks and indexing content that it finds. Examples are: Google, Fast and Alta Vista. - Directories
Will only find sites based on manual submissions. Examples are: Yahoo, Kvasir and Magellan!
Search results are ranked according to relevance to the given search criteria. Some common characteristics are:
- Titles
A search engine will first scan the HTML <title> tag to look for words that match the query. - Beginning content
A search engine will then look for the query words near the top of the document. - Frequency
A search engine will look for frequency of the query words in the whole document.
For more information one search engines go to SearchEngineWatch.com
