Web design is a process of conceptualization, planning, modeling, and
execution of electronic media content delivery via Internet in the form of
Markup language suitable for interpretation by Web browser and display as
Graphical user interface (GUI).
The intent of web design is to create a web site -- a collection of electronic
files that reside on a web server/servers and present content and interactive
features/interfaces to the end user in form of Web pages once requested. Such
elements as text, bit-mapped images (GIFs, JPEGs, PNGs), forms can be placed on
the page using HTML/XHTML/XML tags. Displaying more complex media (vector
graphics, animations, videos, sounds) requires plug-ins such as Flash,
QuickTime, Java run-time environment, etc. Plug-ins are also embedded into web
page by using HTML/XHTML tags.
From: http://www.wikipedia.org