The App Creator provides a faster, simpler way to build applications quickly, easily, and with useful defaults. It also gives us a mechanism to package it up, with any associated configuration, possibly to be exported as an Update Set.
When an application is created, a new entry is made in the Application Picker in the System Menu. This works like an Update Set; when you do a configuration, it gets recorded against that application.
ServiceNow also divides all out-of-the-box functionality into applications, making it easy for you to identify where a record came from. Navigating to System Applications > ServiceNow Applications lets you view the breakdown.
Plugins are used to define an out-of-the-box ServiceNow ...