Software development is the process of conceiving, specifying, designing, programming, documenting, testing, and bug fixing involved in creating and maintaining applications, frameworks, or other software components. While there are many different software development methodologies they all result in the writing and maintaining of source code. This source code is responsible for telling computers what to do when to do it, and how to do it. Without high-quality source code, applications, programs, libraries, and services function improperly and can have devastating real-world impact. Landing on the moon required software that was bug-free, performant, and secure.
A software development methodology is a systematic approach to creating software, writing software, and maintaining software. It's used in the creation of reliable and maintainable commercial software products. Software engineers use knowledge and research-based techniques, such as Test-Driven Development (TDD) to build high-quality systems. Other development methodologies include agile methodologies, such as Scrum and Kanban, and waterfall models. Each methodology aims to create new software functionality while ensuring the application, program, integration, service, or library remains performant, secure, easy to use, and bug-free.
We find that Test-Driven Development (TDD) is the superior method for developing high-quality software that meets all its requirements with fewer bugs, and have adopted a longer tail domain-specific Agile process to manage iterations (application versions) of a project. You can read more research on test-driven development here.
Software development is often a collaborative process, one involving domain experts and technologists. Domain experts provide context, while technologists, engineers, designers, architects, etc… organize the ideas into working software systems.
Once developed, the program will need to be maintained and updated as changes occur to its use within an organization or industry. Software development methodologies allow for software developers to make these changes without breaking existing functionality, reducing security or hindering performance. The better the methodology, the better developers, designers, and engineers are able to maintain existing functionality and the faster they are able to add new functionality.