Maintainability is the ease with which appropriate changes can be made to your code. Unlike a motor vehicle, code does not typically need routine maintenance to avoid things such as rust, but it does, nonetheless, need to be fixed from time to time. Changes to its functionality are also often required, especially when under active development. Much of the code we work on is also being actively worked on by others. This shared ownership relies heavily on the tenet of maintainability.

Making code maintainable should not be a sidelined priority. It is as vital as any other requirement that the code is fulfilling. In the first chapter, we spoke a lot about the importance of considering who your users are. It would be disingenuous not to see that those who maintain and make changes to our code are also our users. They wish to wield what we have created to fulfill a purpose; therefore, they are our users. And, as such, we need to think about how we can best cater to their needs.

In this next section, we'll explore two aspects of maintainability: adaptability and familiarity.