In the Finder, the best way to activate Stacks is by Control-clicking the Desktop and choosing Use Stacks from the contextual menu (below left). If you first click the Desktop, you can also find the commands for Stacks in the View menu: Use Stacks and Group Stacks By. Lastly, if you open the View Options window by Control-clicking the Desktop and choosing Show View Options, you can work with Stacks by choosing from the Stack By pop-up menu (below right).
Regardless, when you activate Stacks, the Finder promptly collects all like icons—even new files, as you create them—together into one or more stacks of icons. Click once on a stack to reveal its contents below. Click again to collapse the revealed icons back into the stack. If you open multiple stacks at once, each subsequent stack takes over a spot at the top of the screen and expands down. If you don’t show disks on your Desktop, you can get a nice columnar view of what’s on your Desktop.
How can you control the order of the files within a stack? That’s a bit trickier. Control-click the Desktop, choose Show View Options, and in the View Options window, choose from the Sort By pop-up menu. We’re partial to Name (for an alphabetical list) and Last Modified (to put the most recent file you’ve touched on top), but see what works for you.
The main problem with Stacks is that it eliminates any spatial memorization you might have relied on to find icons on your Desktop. You might be able to identify the document you’re looking for by its icon, but exactly where that icon appears when you expand its stack depends on what other stacks are open or closed, what other files are in the stack, and how the stack is sorted. So if your Desktop is a mess, but you know to look in the lower-left corner of your Mac’s desktop for the files you’re working with, Stacks may irritate you.
Stacks may not be ideal for everyone, but many people whose Desktops are obscured by icons will appreciate how it cleans things up instantly and keeps everything neat and tidy, with no extra effort on your part.
← So What Are All Those Stacks of Notifications in iOS 12?