Computer software
Software is a program that enables a computer to perform a specific task, as opposed to the physical components of the system (hardware).
This includes application software such as a word processor, which enables a user to perform a task, and system software such as an operating system, which enables other software to run properly, by interfacing with hardware and with other software.
Practical computer systems divide software into three major classes: system software, programming software and application software, although the distinction is arbitrary, and often blurred. Computer software has to be "loaded" into the computer's storage (such as a hard drive, memory, or RAM).
Once the software is loaded, the computer is able to execute the software.
Computers operate by executing the computer program.
This involves passing instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as machine code.
Each instruction causes the computer to carry out an operation -- moving data, carrying out a computation, or altering the control flow of instructions.
Application software
Application software is a defined 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.
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.
Typical examples of software applications are word processors, spreadsheets, and media players.
