OS X Yosemite: Folders that come with your Mac
This folder contains apps, including Mail, Calendar, Safari, and many others. Apps in this folder also appear in Launchpad. If you try to drag an app out of the Applications folder, it isn’t moved. Instead, an alias is created.
This folder contains fonts, Internet plug-ins, and other items used by apps that are available to all users of your Mac. Don’t use this folder to store files and folders you create. Instead, use the Documents folder, iCloud Drive folder, or desktop.
This folder contains the OS X operating system. You can’t change the name or location of the System folder or the items within it.
This folder contains the home folders of all the people set up as users on your Mac. When you’re logged in, the icon for your home folder looks like a house, and the other home folders look like regular folders. If you log out and someone else logs in, that person’s home folder then looks like a house. This folder also contains the Shared folder. Items in the Shared folder are available to anyone who uses your Mac.
Your home folder is named with your user name and has folders for your desktop files, downloads, pictures, documents, movies, music, and any public files.
You can create folders in your Documents folder, iCloud Drive folder, or on the desktop to organize your files. If you can’t create a folder, you may not be able to create a folder in that location. For example, you can’t create folders in the All My Files section of the Finder sidebar.