CLIs are ubiquitous – and they have never been more important. Your guide for a quick tour of CLIs led the creation of .NET Tools, began reshaping the .NET CLI, was a force behind System.CommandLine, and has guided many people in CLI design. You’ll see how all CLIs, including yours, are languages – domain specific languages or DSLs. They also have a special gift for you and your users of strong user expectations leading to fewer decisions for you. You’ll learn easy ways to meet those expectations. Looking to the future, you’ll see how the CLI First design strategy results in human and AI friendly interfaces that are easy to explore and and a good basis for modeling APIs.