What is a functional decomposition diagram (FDD) and why would you use one? Explain how to create an FDD.

What will be an ideal response?

A functional decomposition diagram (FDD) is a top-down representation of a function or process. Using an FDD, an analyst can show business functions and break them down into lower-level functions and processes.
Creating an FDD is similar to drawing an organization chart — you start at the top and work your way down. Figure 4-8 shows an FDD of a library system drawn with the Visible Analyst CASE tool. FDDs can be used at several stages of systems development. During requirements modeling, analysts use FDDs to model business functions and show how they are organized into lower-level processes. Those processes translate into program modules during application development.