Metadata is data about data Embraces and describes a larger body of data XML documents are designed around metadata
• Everything that is not displayed is metadata
<h11></h1>
tags are considered metadata, as they define t the content within them as being a header X/HTML has the <meta> tag • Describes content of the whole webpage Used with search engines
Comes before the <html> tag Necessary to distinguish the version
X/HTML used in the document
of
• Defined in the HTML 3.2 standard
Often
references a DTD -- Document Type Definition
• Separate document containing a set of rules for
structure, syntax and keywords
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml">
Tag
developed to specify information on a web page Does not alter the presentation of data Contains general information May include content such as: • • • •
Expiration date Author name Keywords to be used by search engines Description of the page to display by search engines
<meta
name="name_here“ content="content_here">
<meta http-equiv="name_here" content="content_here">
Requires
name or 'http-equiv' and content to
be valid Http-equiv and name define the general type of information Content defines values of the created information
Equivalent
to an HTTP header Can be used to control the actions of a web browser By using the tag you force your Web server to add or change content in the response header --> the part coming from the server
Value
Purpose
Expires
Defines the expiration of the file in the cashe and when the client will need to request it again Pragma Controls when the page should be put into the cache Refresh Loads the specified page after a number of seconds Set-cookie Creates a cookie in order to collect information Windowtarget
Specifies the location to open hyperlinks in Often used with frames
ď&#x201A;&#x17E; Used
for information types that do not correspond with HTTP headers ď&#x201A;&#x17E; Information will not be entered into the HTTP header, but remain in the XHTML document.
When
a browser requests a page, a response header is produced "keywords" is used to specify words for a search engine "reply-to" specifies an email address for a search engine to use "generator" is often inserted by programs to specify that the document was created in them "author" is used to specify the author of a document
Only
one in four websites use them Use of metadata allows for users to find the site more quickly Not all search engines use metadata • Ones that do have different criteria No
techniques exist that will guarantee you a top listing other than payment for advertisement
Some
search engines search for pages as described by the content attribute when name is set to keywords <meta name="keywords" content="keyword1, keyword2, keyword3"/> Keywords are separated by comas 1000 character limit ---> usually only 250 considered If keywords are repeated, the tag is often ignored
Content
attribute is used to give a short text description of the page to search engines. No more than 25 words or 150 characters <meta name="description" content="text goes here."/>
Used
for pages that should not be indexed by search engines. <meta name="robots" content="noindex"/> "noindex" prevents indexing of the page "nofollow" prevents crawlers from following links to the site "noimageclick" prevents links from going to photos --> it sends them to the page instead "noimageindex" prevents images on the page from being indexed, however the rest of the page is still stored