interface utilisateur graphique
abréviation: IUG

The opposite of Back End, the front end of a site is everything that the user sees and experiences on a web page.

http://www.glaserweb.com/glossary.php

In this context, I think "front end" is used superfluously (and may therefore be omitted), as it is the same as user interface.

Front end: Refers to those functions of a Web site that reside in the client browser rather than in the server. The most basic of these functions is to interpret the HTML code of each page of the site and display the results on–screen.
http://www.jasgraph.com/jasgraph_pages/glossary.html

The back end is the server or host, and the front end is the client or user interface, such as a graphical screen or a Web site. Front end is what the user sees and interacts with for online architectures; the back end is the Web server and its corresponding host computers.
www.payorid.com/glossary.asp

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Note added at 1 hr (2006-03-05 17:20:22 GMT)
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"Bien que la barre de recherche vous permette de trouver ce dont vous avez besoin dans la grande majorité des cas, le menu de recherche offre une interface graphique plus riche pour la recherche."

http://www.neb-one.gc.ca/efile/help/ViewSearchHelp_f.htm

"Le Web offre une interface graphique, l'utilisation de liens hypermédias, que nous décrirons plus loin, de même que l'incorporation du multimédia."
http://chaambi.ifrance.com/dossiers/histnet-c.html