In computer programming, everything a program does can be broken down into three main actions: taking input, processing it, and producing output. This sequence is the basic operation of all computer programs, no matter how simple or complex they are.

Input

Input is the data that a program receives to work with. This can come from various sources like keyboard input, files, sensors, or other programs. For example, if you're using a calculator program, the numbers you type in are the input.

Processing

Processing is what the program does with the input data. This involves following a set of instructions to perform calculations, modify data, or make decisions. The processing stage is where the program applies its logic to transform the input into a useful result. For instance, in a calculator program, processing would be the actual computation, like adding or multiplying the numbers you entered.

Output

Output is the result that the program produces after processing the input. This can be displayed on the screen, saved to a file, or sent to another system. Using the calculator example, the output would be the result of the calculation shown on the display.

Example: Calculating Pay

Let's look at a simple example to illustrate these steps. Imagine a program that calculates pay based on hours worked and an hourly rate:

1. Input: The program asks for the number of hours worked and the hourly rate.
2. Processing: It multiplies the hours worked by the hourly rate to calculate the total pay.
3. Output: The program then displays the calculated pay on the screen.

This basic pattern of input, processing, and output is the foundation of all computer programs.