HTML and CSS Reference
In-Depth Information
However, do not assume that the Web server's operating system dictates everything; for
example, URLs do not use Windows-style backslashes.
Filename
After you specify the server and the directory path for a document, the next step toward
locating it is to specify its filename. Commonly, when a simple directory-based URL is
given like
http://htmlref.com/ch1/
a default file in that directory, often named index.html, will be returned by the Web server.
However, this file could be referenced directly like so:
http://htmlref.com/ch1/index.html
File names are arbitrary,
http://htmlref.com/ch1/reallylongfilename.html
and may be case sensitive, depending on the host operating system. Thus
http://htmlref.com/ch1/reallylongfilename.html
and
http://htmlref.com/ch1/REALLYLONGFILENAME.html
may reference the same object or not, depending on the operating system. Filenames may
include special characters like dashes and underscores,
http://htmlref.com/ch1/really_long_file_name.html
http://htmlref.com/ch1/another-really-long-file-name.html
However, depending on the special characters used, they may be encoded (see the upcoming
section “Encoding” for more information). As an example, the filename “really long file
name.html” with spaces should encode as
http://htmlref.com/ch1/another%20really%20long%20file%20name.html
A dot separates the filename and the
extension,
which is a code, generally composed of
three or four letters that identifies the type of information contained in the file. For example,
HTML source files generally have a
.htm
or
.html
extension, CSS files, a
.css
extension,
JavaScript files, a
.js
extension, JPEG images have a
.jpg
extension, and so on.
http://htmlref.com/ch1/site.css
http://htmlref.com/ch1/bigimage.jpg
http://htmlref.com/ch1/jquery.js
A file's extension is critically important for Web applications because it is the primary
indication of the information type that a file contains. However, it is possible to remove file
