Professional software is not just the programs developed for a customer because the software is almost always packaged with associated documentation such as requirements, design models, and user manuals.
A good or professional software goes beyond software developed solely for a customer. It is usually composed of executable code coupled with documentation and configuration of data that is required to make these programs operate correctly.
A professionally developed software system is often more than a single program. The system usually consists of a number of separate programs and configuration files that are used to set up these programs. It may include system documentation, which describes the structure of the system; user documentation, which explains how to use the system, and web sites for users to download recent product information.
For example, a word processing system consist of executable program, user manual and the document such as requirements and the design needed to produce the executable program.