Page "Software architecture" Paragraph 3

As a maturing discipline with no clear rules on the right way to build a system, designing software architecture is still a mix of art and science.

The “ art ” aspect of software architecture arises because a commercial software system supports some aspect of a business or a mission.

How a system supports key business drivers, described via scenarios as non-functional requirements of a system, also known as quality attributes, determine how a system will behave.

This could be thought of as a parallel to a mission statement and value system in business strategy.

Every system is unique to the business drivers it supports, therefore the quality attributes of each system such as fault-tolerance, backward compatibility, extensibility, reliability, maintainability, availability, security, usability, and such other – ilities will vary with each implementation.