web testing vs client server testing

Web applications are essentially client/server
applications - with web servers and 'browser'
clients. Consideration should be given to the 
interactions between html pages, TCP/IP 
communications, Internet connections,
firewalls, applications that run in web 
pages (such as applets, javascript, 
plug-in applications), and applications 
that run on the server side (such as cgi scripts,
database interfaces, logging applications, 
dynamicpage generators, asp, etc.). Additionally,
there are a wide variety of servers and browsers, 
various versions of each, small but sometimes 
significant differences between them, variations 
in connection speeds, rapidly changing technologies, 
and multiple standards and protocols.
The end result is that testing for web sites 
can become a major ongoing effort.