Computer programs read, modify and manipulate data. But as soon as a program shuts down, whatever data it held in main memory (RAM) is gone.
However, the data often needs to be kept for use at some point in the future. For this to happen, the data needs to be stored in secondary memory i.e. hard disk or other storage medium.
To do this, the data is stored in a file.
This section will discuss the topic of opening, closing, reading and writing files.