David Hill has a nice overview (in the context of software applications):
The term Smart Client was coined to highlight the differences between the typical “Rich Client” applications of yesteryear and the next generation of client applications.
Key capabilities now exist which mean that we can take full advantage of the rich client model, providing the user with an excellent user experience, while at the same time reaping the benefits of centralized deployment and update. In short, this new generation of client applications, the so-called “smart” clients, provides the best of both worlds and adds the intelligence to manage data and connectivity to produce an extremely compelling user experience.
While smart clients provide the benefits of a rich client model with thin client manageability, they also provide much more flexibility than the traditional rich client applications. For example, smart clients need not be designed as monolithic desktop applications. Smart client solutions can be developed that are composed of functionality from more than one client application, with each application collaborating with the others to provide just the right functionality to the user. Such “composite” applications integrate client-side software resources into a coherent solution, or extend the functionality of an existing application to provide smart client features.
In addition, the client platform has moved on in the past few years and now includes many different types of client devices, not just desktop PCs. Such devices include PDA’s, SmartPhones, Tablet PCs, Laptops, set-top boxes, automotive devices, retail terminals, and so on. Smart client applications can be built to take maximum advantage of the features provided by the host device and tuned to provide the best user experience for the typical users of these devices.
If a client application displays these characteristics, then it can be said to be smart:
– Utilizes Local Resources
– Offline Capable
– Intelligent Install and Update
– Client Device Flexibility