Finder likes to keep things clean. Unless you flip hidden switches – accessible in many general-purpose utilities – you only see the files and folders which you’re supposed to. And most of the time, that keeps life clean and simple, as you don’t want your windows cluttered up with $RECYCLE.BIN, .parallels-vm-directory, git, usr and var. But when you do need to access those hidden files and folders, it can be hard to remember just how.

Here’s a quick summary.

~/Library

Of all the hidden folders on your Mac, your Home folder Library is probably the one you access most frequently:

• hold the Option key down while opening the Finder’s Go menu,
• in the Go menu, use Go to Folder… and enter ~/Library,
• use any method for showing hidden items, and select it in your Home folder.

Any others

The following are probably the best:

• in the Finder, or any file open or save dialog, press Command-Shift-. (period or stop) to reveal hidden items, then press the same keys to hide them again;
• in the Finder’s Go menu, use Go to Folder… and type in the full pathname, such as /var/db. Use normal path conventions, notably ~/ as shorthand for your Home folder, and preface paths with a slash / to start at the root level.

The Command-Shift-. shortcut is new from Sierra on, and a valuable timesaver.

Some apps provide custom menu or dialog options to enable you to navigate hidden items: BBEdit, for example, has an option to show and access hidden items, and will open any type of file for which you have read permission.

What about SIP and permissions?

System Integrity Protection, or SIP, doesn’t stop you from seeing or reading the files which it protects, but blocks all attempts to change or remove them. If you want to edit a file which is protected by SIP, the best way to do that is to copy the file, perhaps to your Documents folder, and open that copy, which is a wise move if you want to study it anyway.

Permissions can be more obtrusive, though, as they will lock you out of some folders, shown in the Finder with a red-and-white ‘no entry’ sign. You can’t use the Finder’s Go command to bypass those, as they’re imposed at the heart of macOS. Should you need to see inside a folder which denies you permission as an admin user, you’ll need to take to Terminal’s command line and obtain root privileges. There’s no mechanism for elevating your privileges like that in the Finder.

(Thanks to Phil Stokes at applehelpwriter for the hint on Sierra’s helpful shortcut.)