The OS X Mountain Lion Folder Structure
Look at the folder structure of a typical OS X Mountain Lion installation. Open a Finder window, and click the icon for your hard drive (which is typically called Macintosh HD) in the Sidebar. You should now see at least four folders: Applications, Library, System, and Users.
Within the User folder, each user with an account on this Mac has his own set of folders containing documents, preferences, and other information that belongs to that user and account.
If you’re the sole person who accesses your Mac, you probably have only one user. Regardless, the folder structure that OS X uses is the same whether you have one user or dozens.
Within the Users folder, you find your personal Home folder and a Shared folder, where you can put files you want to share with other users. All these files are stored in a nested folder structure that’s a bit tricky to understand at first. This structure makes more sense after you spend a little time with it and figure out some basic concepts.
If you display the path bar at the bottom of your windows by choosing View→Show Path Bar, it’ll start to make sense much sooner.
If you take a look at the following figure, you can see how these main folders are related to one another.