HTML and CSS Reference
In-Depth Information
Character
Description
Usage
Encoding
[
Left square bracket
Unsafe
%5B
]
Right square bracket
Unsafe
%5D
'
Back single quotation mark
Unsafe
%60
In general, you should always encode a character if there is some doubt
as to whether it can be placed as is in a URL. As a rule of thumb, any
character other than a letter, number, or any of the symbolic characters
like
$-_.+!*'( )
should be encoded.
It is never an error to encode a character, unless that character has a
specific meaning in the URL. For example, encoding the slashes in an
HTTP URL causes them to be used as regular characters, not as path-
name delimiters, breaking the URL. Similarly, encoding an ampersand
when it is used as a parameter separator in a URL will defeat the inten-
ded purpose. Instead, write these ampersands using
&
to keep their
intended function intact.
6.2.2. Absolute and Relative URLs
You may address a URL in one of two ways:
absolute
or
relative
. An
absolute URL is the complete address of a resource and has everything
your system needs to find a document and its server on the Web. At the
very least, an absolute URL contains the scheme and all required ele-
ments of the
scheme_specific_part
of the URL. It may also contain any
of the optional portions of the
scheme_specific_part
.
With a relative URL, you provide an abbreviated document address that,
when automatically combined with a base address by the system, be-
