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". So `fastn` is all that for you, and more. So let's install it now. If you are using `OSX` or `Linux`, installing it can be as easy as running the following in the terminal:

sudo bash -c "$(curl -fsSL https://raw.githubusercontent.com/fastn-stack/fastn/main/install.sh)"