What is Application Virtualization? | VMware Glossary

Application virtualization is a process that deceives a standard app into believing that it interfaces directly with an operating system’s capacities when, in fact, it does not. 

This ruse requires a virtualization layer inserted between the app and the OS. This layer, or framework, must run an app’s subsets virtually and without impacting the subjacent OS. The virtualization layer replaces a portion of the runtime environment typically supplied by the OS, transparently diverting files and registry log changes to a single executable file.

By diverting the app’s processes into one file instead of many dispersed across the OS, the app easily operates on a different device, and formerly incompatible apps can now run adjacently. 

Used in conjunction with application virtualization is desktop virtualization—the abstraction of the physical desktop environment and its related app software from the end-user device that accesses it.