A web client is sometimes called a thin client. Thin 
clients usually do not query databases, execute complex 
business rules, or connect to legacy applications. When you 
use a thin client, such heavyweight operations are off-
loaded to enterprise beans executing on the J2EE server, 
where they can leverage the security, speed, services, and 
reliability of J2EE server-side technologies.

A thin client application is the one where in the business 
logic is not included in the client code. The client code 
only contains the presentation logic.

The Thin application client provides a lightweight, 
downloadable Java application run time capable of 
interacting with enterprise beans.

The Thin application client is designed to support those 
users who want a lightweight Java client application 
programming environment, without the overhead of the J2EE 
platform on the client machine. The programming model for 
this client is heavily influenced by the CORBA programming 
model, but supports access to enterprise beans.