Mosaic User's Guide
Concepts & Terminology
The World Wide Web (WWW or W3)
The World Wide
Web project was initiated by Tim
Berners-Lee of CERN, Switzerland. The project attempts to provide an
interface to the existing communication protocols (FTP, Telnet, WAIS, Gopher,
NNTP, etc.) as well as the existing data formats (GIF images, Postscript
documents, AIFF sounds, etc.) in one package.
In addition, the WWW project introduces a new protocol to the global Internet,
the HyperText
Transfer Protocol (HTTP), and a new file type, the HyperText Markup
Language (HTML).
NCSA Mosaic is one WWW client (or
browser) that can
communicate with HTTP servers, as well
as servers of the more traditional protocols.
Uniform Resource Locators (URL)
The mechanism by which Mosaic can retrieve information resources from anywhere
on the Net is the Uniform Resource Locator (URL). URLs combine a path and
filename with the name of the machine that serves the file to the Net, as well
as the protocol to be used to retrieve the data. Here is a Beginner's Guide to
URLs.
HyperText Markup Language (HTML)
The HTML documents viewed with Mosaic are simply text files with special
markup tags in <brackets>. For example, <b>bold</b>
produces the output: bold; and <i>italics</i> produces
italics. Hyperlinks are created with the a tag, for anchor,
with embedded URLs. To see the HTML source of any document viewed with
Mosaic, use the View Source feature under the File menu. For
more information, see A
Beginner's Guide to HTML.
Hyperlinks & Multimedia (Hypermedia)
NCSA Mosaic can view hypertext HTML documents, in which words or inlined images can act as hyperlinks to other documents. Hyperlinks can also point to
images, sound files, movies, HDF files, and more. When a hyperlink is
selected that points to a resource which Mosaic cannot handle internally, it
attempts to send the data file to an external viewer. For example, GIF images
are sent, by default, to the program xv, a commonly-used image viewer.
Most sound files are sent, by default, to the showaudio program.
Mosaic's use of external programs to handle specific data types is completely
configurable. Click here for more information on
the default external viewers and configuring Mosaic's multimedia
capabilities.
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National Center for Supercomputing Applications
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