We’re back with video 10 in our series designed to jump-start your understanding of the core principles and practices of Agile software engineering (ASE). This time, one of our Lean-Agile thought leaders, Ken Pugh, talks about aspects of design quality that are critical for maintainability. Ken introduces Interface-Oriented Design by discussing one of the most important guiding principles—design to interfaces not implementations—from Design Patterns by Gamma et al. Next, he draws from another classic book.