Note that an unresponsive process is labelled with (Not Responding). To make finding the culprit easier, click Process Name in the column header to sort them alphabetically, or use the Search field in the top-right corner of the window to find the app or process.

Under the Process Name list, select the app or process you want to quit.

If you're having issues with a particular app or process (if it's frozen/unresponsive, for example) Activity Monitor allows you to kill it. Note that the columns available to you will depend on whether you're using a desktop or a notebook Mac. To display more columns, select View -> Columns in the menu bar, then choose the columns you want to view. You can click the triangle next to an app's name to display all the child processes under the parent application.

That's because you're seeing the list being updated every five seconds to show changes in individual app usage statistics. You'll notice the order jumps around a lot. The main window lists all the apps and processes currently running on your Mac. You can find the Activity Monitor on your Mac in the /Applications/Utilities folder. If you're on a portable Mac and you have suspicions that an app is sapping your battery, Activity Monitor can help you identify it. With the Activity Monitor app in macOS, you can force quit misbehaving apps, find out how much energy your Mac is using, and see which apps or processes are eating the most processor cycles.

Macos process monitor