The Portmaster UI is the main way you interact with the Portmaster Application. It connects to the Portmaster Core Service, which is running in the background. Through the Portmaster UI you can easily monitor network activity on your device, block domains and connections as well as configure settings and rules.
The Portmaster UI has no background activity in order to save your precious computing resources. Background interaction is being take care of the Notifier.
Extended documentation of the Portmaster UI are yet to be written. You can check out its source code in the mean time.