A subclass of computer software that employs the capabilities of a computer directly to a task that the user wishes to perform.
This should be contrasted with system software which is involved in integrating a computer’s various capabilities, but typically does not directly apply them in the performance of tasks that benefit the user.
In this context the term application refers to both the application software and its implementation.
A simple, if imperfect, analogy in the world of hardware would be the relationship of an electric light (an application) to an electric power generation plant (the system).
The power plant merely generates electricity, itself not really of any use until harnessed to an application like the electric light which performs a service that the user desires.