On OS X El Capitan, what is the difference between /Library/ and /System/Library/?

Question

There are two 'Library' directories in my OS X 10.11 installation, one being /Library/, the other being /System/Library/.

What is the difference between different Library folders?

Answer 1

As in all the Unix system, there are two type of lib folder.

One specific for the user and the other for the entire system and so all the users of the machine.

In particular for OS X: the Macintosh HD version is the actual computer Library, while, the home folder version is specific to your user account.

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Here an example to help you understand how to use it:

/System/Library is a place to store fonts, screen savers, Dashboard widgets, and all other things that all local users need access to.

~/Library is for your own user account only (cache and preference files, widgets for your use only, etc).

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EDIT: taken from here, a complete overview of all the possible library folders in a Mac OS X system:

• The user library, ~/Library, stores per-user settings etc.

• The local library, /Library, stores computer-wide settings and all-users content etc. I call this the "local" library, because in NextStep it was /Local/Library, but you'll see all sorts of other names for it, such as the root library, computer library, ...

• The network library, /Network/Library would store settings shared by all computers in a network domain -- if a network domain admin set one up, which nobody does anymore...

• The system library, /System/Library, stores the base settings, resources, etc that come with OS X. In theory, you shouldn't change anything in here.

Answer 2

/System/Library is for stuff that doesn't change and is installed by Apple. Files here help the operating system run.

/Library is for things that may change and that pertain to all users on a computer.

And for completeness (although not mentioned in the question):

~/Library is where things that may change specific to a particular user go.

Answer 3

macOS has 3 types of Libraries.

Here are the following:

/Library/ - Used to control system wide settings that are used by all users

Usually no reason for regular user to alter, although applications will alter this during and post installation

/System/Library/ - Same as /Library/ but protected by SIP. Used by macOS as the core Library. Most things in there are required by macOS.

Shouldn't (and can't without SIP being disabled) be altered.

~/Library/ - Same as /Library/ but for user specific things (Each user has one.

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You can access each of these by going to Finder>Go>Go To Folder and typing in their respective path.