Software development (also known as application development, software design, designing software, software application development, enterprise application development, or platform development) is the development of a software product. The term "software development" may be used to refer to the activity of computer programming, which is the process of writing and maintaining the source code, but in a broader sense of the term it includes all that is involved between the conception of the desired software through to the final manifestation of the software, ideally in a planned and structured process. Therefore, software development may include research, new development, prototyping, modification, reuse, re-engineering, maintenance, or any other activities that result in software products.
Questions having the development tag regards the development ov custom code in SharePoint environment.
Reference: Wikipedia - Software development