To write programs using ftd language you will have to use fastn, a command line program, like ls we mentioned in previous section. fastn is a “compiler” or “interpreter” of ftd, it converts your ftd programs to html, css, js that browsers understand. fastn is also a “package manager”, when you are writing programs, you often depend on code written by others, shared by them to make life easy by everyone. Code you depend on others is called dependencies or libraries. We call them fastn package. And fastn manages these packages. This will all make sense more sense as we progress in the book, what you need to know is that fastn acts as your package manager as well. And finally fastn is a “web server”, when you write a web application or a website, you are trying to create something that works in web browsers like Chrome, Firefox, Safari, etc, and these browsers talk to “web servers”.