About Hyperlinks in HTML...
= Index DOT Html by Brian Wilson =

Justification | Absolute Vs. Relative URLs | URL Encoding
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Justification for Hyperlinks
Hyperlinks are the heart of HTML. They allow the linking together of remote documents with the convenience of a click or other activation mechanism. Hyperlinks are used to establish a relationship between two documents: a source (usually the current document) and the destination. The destination of a hyperlink jump can be either an entire document or a specific location within a document. In addition, the hyperlinking element (A) can play the role of destination for a URL (using the NAME or ID attribute), the activation point to another URL (using the HREF attribute), or both at the same time.

The A element has many other attributes as well (such as TARGET) which serve to further communicate information about the source and destination documents.
Absolute Vs. Relative URLs
A hyperlink destination is defined as a Uniform Resource Locator (URL) using this general format:
[protocol]://[network location ID]/[path on machine]/[file name]?[query string]#[internal document location]
This is only a general format for specifying a URL - There are many variations within this framework (such as a "mailto" URL), and portions of the format can be omitted (such as the [internal document location].) Please see RFC1738 for more details on URLs.

The path to a document can ALSO be specified relative to the originating document. In such cases, the [protocol] and [network location ID] portions of the above syntax are omitted and [path on machine] is given relative to the current file or to a complete URL referenced in the BASE element.
URL Encoding
URLs only allow a subset of allowable ISO-8859-1 (ISO-Latin) characters to be used. Any other characters must be encoded using a special escape syntax that uses combinations of the allowable subset. A separate page in the Topics section covers URL encoding in much greater detail, and even provides a little utility to automatically create URL encodings of characters.

Related Sites
Official References
RFC 1866: The HTML 2.0 specification (plain text)
The web version of the HTML 2.0 (RFC 1866) specification
The HTML 3.2 (Wilbur) recommendation
[Includes all HTML 2 character elements and newer formatting elements in common use]
The HTML 4.0 Recommendation
[Includes all 2.0, and 3.2 elements plus many new features]
RFC 1738: Uniform Resource Locators (URL)
[RFC explaining different allowed URL protocols]
RFC 1808: Relative Uniform Resource Locators
[Another RFC explaining different allowed URL protocols]
Netscape Frames Discussion Document - Targeting Windows
Internet Explorer Tag reference
[Details hyperlink usage including common extensions]

Other Related Links
Yahoo's UR* index

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