Answer Description

Task Manager (taskmgr.exe) is an application on Windows operating systems that can be used to quickly view resource utilization like Network, CPU, Memory and Disk utilization. It is a quick option to view what the cause of the slowness is, for example you may find that the NIC card has very little bandwidth available or that a certain application is taking up a high percentage of the CPU.

Wikipedia

In operating systems, a task manager is a system monitor program used to provide information about the processes and applications running on a computer, as well as the general status of the computer. Some implementations can also be used to terminate processes and applications, as well as change the processes' scheduling priority. In some environments, users can access a task manager with the Control-Alt-Delete keyboard shortcut. Task managers can display running services (processes) as well as those that were stopped. They can display information about the services, including their process identifier and group identifier.