Until about mid 1993, if you wanted to access a gopher service, you had to use a gopher program. If you wanted to access anonymous ftp, you had to use an ftp program. Then came mosaic....
Mosaic is an X-windows program that combines access to gopher, ftp, Usenet news (though not the ability to post messages - yet) telnet and most importantly, http servers.
http stands for HyperText Transfer Protocol (I think). A hypertext document includes special text that when clicked on with the mouse, causes something to happen. If you have used the help system under Microsoft Windows, then you will be familiar with the idea of jumping from one page to another by clicking on highlighted words. The event that happens when you click on some text in a document that is provided by an http server, might take you to another part of the same document, to another document on the same server, to a document on a server somewhere else in the world, to an image, sound clip or movie. The interconnections between documents on the Internet form a web and this has become known as the World Wide Web, WWW or W3 for short. Accordingly, Mosaic is known as a WWW browser, other WWW browsers exist, see below.
Documents of this type are written in HTML (HyperText Markup Language). This has a fairly simple syntax. Tutorials in writing HTML documents can be found on the Internet. The protein structure group at York has a particularly nice introductory text on this subject. You can reach this via my server under the "useful links" link.
Links in the hypertext document are specified using a URL (Uniform Resource Locator). A URL may point to another http server, a gopher, ftp or local file. For example, the bibliography file on my server would be defined as: URL="http://www.compbio.dundee.ac.uk/bibliography.html". The README file on my ftp server is URL="ftp://www.compbio.dundee.ac.uk/README" and so on.
On the VMS cluster you start mosaic from an X-terminal session by typing prep mosaic, then mosaic. When the program starts up it creates a window on the screen with the LMB home page. You can move to other information by clicking on the blue (or underlined) words. If a link is made to a very remote computer, then it can take some time for the connection to be made and the data to be transferred. If you are can't wait, then click on the rotating world in the top right hand corner to cancel the connection.
A good starting point for browsing or surfing the Web is the OCMS server. This is listed on both the LMB and Barton Group WWW pages.