File structure A good file structure makes it easy to navigate, maintain, and extend. It’s also important that the file structure be self-documenting and clearly indicate intention. Someone should be able to look at the file structure and quickly have a high-level understanding of what elements make up the app and what the app does. CLEAN CODE One our favorite programming books is Clean Code: A Handbook of Agile Software Craftsmanship by Robert C. Martin (2009, Pearson Education). We recommend that everyone read it.