As a default, XStudio is supplied with XEngine, an audio playback engine that handles the actual playback of audio files. This separates the task of playing audio from the main application, which manages which audio items to play and when they are to be played or stopped, along with coordinating automated activity.
In fact, if you close XStudio while audio is playing and do not close XEngine, the audio will continue to play until playback is completed. This provides the flexibility to close XStudio for one reason or another, then restart the program before XEngine has completed playing whatever was playing when you closed XStudio.
Generally, you need not be concerned with XEngine under normal use of XStudio. However, there may be occasions where you need to work with XEngine directly. This section covers particulars on launching XEngine, the XEngine user interface, and a history of revisions to the audio engine.