Like the Task Manager, the Mac Activity Monitor also lists all of the processes that are running on the system. You can open it by going into Applications and selecting Utilities, or searching for it directly in Spotlight by clicking on the magnifying glass in the upper-right corner of the menu bar.
The Mac Activity Monitor is split into several sections: CPU, Memory, Energy, Disk, Network, and (in later versions) Cache. The list of processes includes user apps, system apps used by the operating system, and invisible background processes. You can choose which columns to display and filter the processes by going into the “View” menu. As well as the Mac Activity Monitor, you can also install other programs such as htop to manage system processes.