Application Software are the software that accomplish a single type of task properly and they are always executed under the control of an operating system. It means, if there is no operating system on a computer system or device, the application would not be able to accomplish the task for that it was developed because it always executes over the operating system layer.
The specialty of the application software is that they accomplish only one kind of task and they are developed to achieve only a single goal. No any other kind of task could be performed with the application if that have not been developed for that.
For example, Tally is an Accounting Application Software, so you can use it for accounting only. You can’t use it for image processing or document typing. Similarly, Photoshop is also an example of Image Processing Application Software, so you can use it for image processing only. You can’t use it for accounting or document writing.