A logical design defines what must take place, not how it will be accomplished. Logical
designs do not address the actual methods of implementation. In contrast, a physical
design is like a set of blueprints for the actual construction of a building. Typically, a
physical design describes the actual processes of entering, verifying, and storing data; the
physical layout of data files and sorting procedures, the format of reports, and so on.
Because logical and physical designs are related so closely, good systems design is
impossible without careful, accurate systems analysis. For example, you might return to
fact-finding if you discover that you overlooked an important issue, if users have
significant new needs, or if legal or governmental requirements change.