My attention was brought to a process named indicator-application-service because it was idling at 28% CPU usage. What does this program do?
indicator-application-service is the service that is used to manage application indicators. Application indicators are a way for applications that don't provide any indicator integration with any of the existing indicators such as Messaging, Session, DateTime, etc. You can think of it as the replacement for the former systray.
Applications that want to provide status that doesn't fit into the existing categories can register with indicator-application-service and get an icon displayed in the panel.
