It's one thing to create a directory, but what if you need several? We can do that!
Back in Terminal enter the following commands:
cd ~/Desktop mkdir 3 1 2
Now take a look at your Desktop, either with Finder or here in Terminal. You should see 3 new directories as you named them - k00l!
Not done yet. What if we want to make a directory that contains another one?
mkdir -p 4/5/6
Now you have a directory named 4 that also contains a directory 5, that also contains a directory 6.
Now that you've cluttered up your Desktop with some oddly-named directories, let's get rid of them.
rmdir