The Application Virtualization Client is the component that actually runs the virtual applications. The Application Virtualization Client enables users to interact with icons and to double-click file types to start a virtual application. It also handles streaming of the application content from a streaming server and caches it before starting the application.
There are two different types of Application Virtualization Client software: the Application Virtualization Terminal Services Client, which is used on Terminal Server systems, and the Application Virtualization Desktop Client, which is used for all other computers.

Ensure that the client cache is large enough to handle the applications being assigned to the user. If the cache is not scaled properly, then the user can experience application failures when disconnected. This occurs because the cache may have flushed the application in preference for another more recently run application. The client cache can be modified through the Desktop Configuration Client, which is installed with the App-V client on the workstation. The maximum cache size is 1 terabyte.

Figure: App-V Desktop Client

App-V Universal Desktops clients turns desktop applications into services, deployed on demand without conflicts, and centrally managed with real-time license compliance.

   •  Make existing Windows applications immediately available as centralized virtual application services over networks including LAN, WAN, VPN, wireless and Internet; all without rewriting any source code.
   •  Eliminate significant deployment issues, application and system conflicts.
   •  Enable different versions of the same application to run on the same desktop.
   •  Enable the same application with different configurations to run on the same desktop.
   •  Enable operating systems to be configured as read-only, yet still allow applications that require full rights to run properly.
   •  Centralize application provisioning, licensing and updates.
   •  Scale to thousands of users from a single server.
   •  Include fail-over protection: in the event of a network outage, connected users are able to continue working, since code resides on the local computer.

The App-V Client is one of several Microsoft products whose interoperation puts Windows-compatible applications into the hands of Users.

The following figure shows the App-V for Terminal Servers Client, installed on a Windows-based Terminal Server computer, in its relation both to a App-V Virtual Application Server computer and to a terminal computer and Windows computer in the App-V Platform.

The App-V Client’s purpose is twofold. The App-V Client conveys requests for App-V-enabled Windows-compatible applications to a App-V Virtual Application Server from Users at a Terminal Server’ s terminal and/ or RDP/ ICA Client computers. As soon as the Virtual Application Server begins to stream a requested application, the App-V Client begins the application’ s launch, as if the application was locally installed. Simultaneously, the Terminal Server displays this launch (either in a desktop replacement or a seamless window) to the requesting User’s terminal or RDP/ ICA Client computer, as if this application’ s launch and subsequent running was occurring on the User’ s computer.

In the figure above, the Virtual Application Server can deliver App-V enabled applications both indirectly (to a terminal or an RDP/ ICA Client computer) and directly (to a computer that is not only an RDP/ ICA Client, but also a App-V for Windows Desktops Client). The latter configuration is called "App-V Dual Mode".