By default when you open your Terminal you’ll be inside the /Users/UserName directory. But what if you need access to the root directory of your Mac?
Well, you can always cd .. a couple of times, to move backwards from /Users/YourUserName to / (the root).
But that’s a waste of time, instead run this command:
open /This will open a Finder window at the very root of your Mac computer, which gives you access to the Macintosh HD, Network and Remote Disc directories.