This question comes up constantly. You have a dozen apps open, your Mac feels sluggish, you close a few windows, and nothing changes. It feels like it should help. The frustrating truth is that on macOS, closing a window and quitting an app are two very different things.
Shiny is a small menu-bar tool for managing memory pressure, which means a lot of attention has gone into how macOS actually handles RAM (the temporary workspace your Mac uses to hold what's running). The conventional wisdom is half right; understanding the other half makes a noticeable difference.
What's the actual difference between closing and quitting?
On macOS, clicking the red circle in the top-left corner of a window closes that window. The window disappears. But the app itself remains running in the background, loaded in memory, waiting for you to open a new window or bring it back.
This catches people who switch from Windows, where closing the last window usually exits the program. On Mac, you'll often notice a small dot under the app's Dock icon even after the window is gone. That dot means the app is still running.
To actually quit an app and free its memory, you have two options: press Command-Q while the app is in the foreground, or right-click the app's Dock icon and choose Quit. Either way, the app exits and its memory is released back to the system.
If you've been clicking the red X and wondering why your Mac never feels faster, this is likely why.
Why doesn't quitting an app free all its memory?
Here's where things get a little counterintuitive. You quit an app, open Activity Monitor (press Command-Space and type "Activity Monitor"), click the Memory tab, and notice that "Memory Used" hasn't dropped much. What's going on?
macOS has a philosophy: unused RAM is wasted RAM. Rather than immediately wiping the memory an app was using, macOS often compresses it and keeps it around for a while. The idea is that if you relaunch the same app in the next few minutes, it can restart much faster from that compressed state than if it had to load everything from scratch.
This is a sensible design. It makes your Mac feel snappier day-to-day. But it means "Memory Used" in Activity Monitor can stay deceptively high even after you've quit several apps.
The number to watch instead is the Memory Pressure graph at the bottom of the Memory tab. Pressure is the honest signal. It tells you whether your system is actively struggling to find enough RAM, not just how much happens to be allocated at any given moment. What memory pressure actually means is covered in detail in a separate post if you want to go deeper.
When does quitting apps actually help?
Quitting apps makes a real, meaningful difference in two situations.
When an app has a memory leak. Some apps gradually consume more and more memory the longer they run, a problem developers call a memory leak. The app keeps asking for more RAM and never gives it back. Common offenders include Chrome with many tabs open, Slack after a full day of use, Microsoft Teams, and occasionally Photoshop or Lightroom during a long session. Quitting one of these and relaunching it can free a significant chunk of RAM and noticeably reduce memory pressure. If your Mac slows down over the course of a day but feels fine after a restart, a leaky app is the likely culprit. See the guide on how to free up RAM on Mac for a step-by-step approach.
When you've opened more apps than your Mac has RAM to comfortably hold. If you're running a video editor, a browser with 20 tabs, and a design tool all at once on a Mac with 8 GB of RAM, you will hit genuine memory pressure. Quitting one of those apps frees its active memory and eases the pressure. In this case, the Memory Pressure graph will shift from yellow or red toward green, which is a real improvement you'll feel.
For everything else, moderate RAM use with green pressure, quitting apps is optional. macOS manages the situation fine without your help.
What works better than closing apps?
If your goal is a faster Mac, here are the things that make a more reliable difference than closing windows:
Restart occasionally. A weekly restart clears compressed memory, resets leaky apps, and gives macOS a clean slate. It's the most effective single thing most people can do.
Watch Memory Pressure, not Memory Used. Open Activity Monitor and look at the Memory tab. If the pressure graph is consistently green, your Mac's memory situation is fine, even if "Memory Used" looks high. How to use Activity Monitor on Mac walks through what each reading actually means.
Identify the leaky app. If pressure goes yellow or red during the day, sort the app list in Activity Monitor by "Memory" to find which app is using the most. Quitting that specific app is more effective than closing a dozen unrelated windows.
Reduce browser tabs. Browsers are the single biggest consumers of RAM on most people's Macs. Each tab is essentially a small running program. Keeping 5 tabs open instead of 50 makes a bigger difference than quitting most other apps.
Apple's own documentation on checking whether your Mac needs more RAM is a useful reference if you want to go further with Activity Monitor.
Should I quit apps every day?
It depends on which apps and how your Mac is coping.
If your memory pressure graph stays green throughout the day, there's no need to make a ritual of quitting apps. macOS is handling things. Let it.
If pressure goes yellow or red by mid-afternoon, it's worth identifying which app is responsible (Activity Monitor, sorted by memory, will tell you) and quitting it. That's a more targeted approach than blanket-quitting everything and is less disruptive to your workflow.
The one habit that is genuinely worth building: quit Chrome, Slack, Teams, or any other known memory-leaker at the end of the day, or at least restart them in the morning. These apps don't get better with time. The longer they run, the more memory they tend to hold.
If you find yourself doing this check repeatedly throughout the day and wish something could handle it more quietly, that's the gap a tool like Shiny fills. It sits in your menu bar, shows you pressure at a glance, and frees memory in one click when things get tight. You can read more about how that compares to the broader category of Mac cleaners if you're trying to decide what's worth paying for.
Bottom line
Closing a window with the red X does not free RAM on Mac. The app keeps running.
Quitting an app (Command-Q, or right-click the Dock icon and choose Quit) does free its active memory. The drop in "Memory Used" might be smaller than expected because macOS compresses recently-used memory for faster relaunches, but the improvement is real.
The most useful thing to watch is the Memory Pressure graph in Activity Monitor, not "Memory Used". Green pressure means your Mac is fine. Yellow or red means something is genuinely competing for RAM, and that's when quitting the right app will make a noticeable difference.
For most people, the bigger wins come from restarting weekly, reducing browser tabs, and quitting known memory-leakers like Chrome and Slack at the end of the day. If you want a broader explanation of what makes Macs slow, that post covers the other common causes beyond memory.