With Java 9, modularity comes to your doorstep (whether you ordered it or not). This isn't your average language feature: making the most out of it may involve rewiring your brain. In this session we explore the benefits of a modular codebase using Java 9 modules. Because who doesn’t like more reliable and secure applications, meanwhile killing the dreaded classpath? After reviewing the basic concepts of modules, we'll explore modularity patterns that enhance your design and development skills. We all have existing software, so migration of codebases to a modular world is an important topic as well. Automatic modules, the 'unnamed' module and other new concepts are added to your toolbox to this end. Want examples? We've got plenty in this practical and code-driven talk. Even if you intend to use Java 9 without modules, this talk helps you prevent common issues. You'll be ready for Java 9 before you know it.