Mac Inside & Out · Activity Monitor & Storage · Lesson 1 of 5

Getting to Know Activity Monitor

See what keeps your Mac busy, and close a stuck app safely.

Five tabs, one busy Mac

When a Mac feels slow, something is usually working hard. Activity Monitor is the Mac app that shows you what. On Windows, Task Manager does the same job.

To open it, press Command+Space to open Spotlight. Type "Activity Monitor" and press Return.

Each row is a process. A process is a program, or part of one, that is running right now. Across the top are five tabs:

• CPU: how hard each process makes the processor work. The processor is the chip that does the computer's thinking.
• Memory: how much working space each process uses. This short-term space is called RAM.
• Energy: how much battery power each app uses.
• Disk: how much each process reads from and saves to storage.
• Network: how much each process sends and receives over the internet.

Click a column title, like % CPU, to sort the list. Click it again to flip the order. The biggest users rise to the top.

A number that jumps for a few seconds is normal. Opening an app or a web page makes the processor work hard for a moment. Pay attention when one app stays near the top for a long time and the Mac stays slow. That is a runaway app.

On the practice computer, open the CPU tab, sort by % CPU, and find the app using far more than everything else.

Memory Pressure and Force Quit

Click the Memory tab. At the bottom is a small graph called Memory Pressure. It shows how hard your Mac is working to fit everything into its RAM.

The color tells the story:

• Green: your Mac is using its memory well. There is nothing to do.
• Yellow: worth watching. Closing a few apps or browser tabs may help.
• Red: your Mac needs more memory than it has. Close apps you are not using.

Don't worry if "Memory Used" looks almost full. Macs use spare memory to speed things up. The color matters more than that number.

Sometimes an app freezes. You may see a spinning, rainbow-colored pointer that won't go away. First, wait a minute. Then try to quit it normally with Command+Q.

If that fails, you can Force Quit. That makes an app close right away. In Activity Monitor, select the app, then click the X button at the top of the window. Choose Force Quit. You can also press Option+Command+Esc from anywhere.

Force Quit can lose unsaved work in that app, so use it only when an app is truly stuck. Leave processes you don't recognize alone. Many of them belong to macOS itself.