Highly maintainable code is hard to produce.
Without maintainability we can not have sustainable code, it will rot and have to be re-written. As an industry we're often given principles to follow which sound FANTASTIC... but don't layout the "how" of reaching these ideals.
We'll go into detail of four technical practices that have the biggest impact towards improving maintainability of the code we write.
As agile developers, what we want to do is deliver value to the customer quickly and consistently. As an agile developer and team, coding technical practices are the only way to develop code to quickly and consistently deliver value to the customer for the life of the product.
These technical practices produce simple, understandable, testable code which results in extremely maintainable code that we'll be able to enjoy working on for a long time.