Input –Process - Output

A computer program uses the input-process-output. The IPO model receives inputs from a user or some other software or hardware. It performs the computations on the inputs and returns the output of the computations.

​​​​​​​In other terms, programs take raw data to process them and produce information.

​​​​​​​The system divides the entire process into three categories these are

Input - Requirement 
Process - Computation to produce the desire outcome
Output - A desire outcome.

Example :  

A program that calculates the simple interest. Following the IPO model, the program must do the following

Input   - Ask the user for the principal, rate and time 
Process - Perform a calculation using P(1 + rt) 
Output  - Display the simple interest.