The Input-Process-Output Model also known as the IPO+S Model is a functional model and conceptual schema of a general system. An IPO chart identifies a program’s inputs, its outputs, and the processing steps required to transform the inputs into the outputs.
The IPO model has many interdisciplinary applications, and is used to convey systems fundamentals in IT overview education and as a brainstorming, preliminary investigation tool in systems development processes such as the SDLC. It consists of at least three, and sometimes four, distinct components. In contemporary Information Technology, it is almost always discussed as a four component model in which the fourth is a named optional.
The components of the IPO model are defined as:
I: Input - The information, ideas, and resources used
P: Processing - Actions taken upon/using input or stored material
O: Output - Results of the processing that then exit the system
S: Storage - Location(s) where material inside the system is/are placed for possible use at a later time