The term application posture characterizes the nature of a software application's interaction with its user.
The term was coined by software design visionary Alan Cooper, who characterized four 'postures' for applications: sovereign, transient, daemonic and parasitic.
A sovereign application is a program that monopolizes the user's attention for long periods of time.
Cooper defined transient applications thus: 'A transient posture program comes and goes, presenting a single, high-relief function with a tightly restricted set of accompanying controls. The program is called when needed, it appears and performs its job, then it quickly leaves, letting the user continue her more normal activity, usually a sovereign application.'
These classifications are key when designing an object-oriented user interface because such an interface may not be suitable for a transient application.