Task Manager is a useful tool that allows you to force close applications, see a list of applications causing performance issues, look at your CPU memory usage and last boot time, disable startup applications, and much more.
To open Task Manager, go to the bottom left of desktop and use the search function to lookup 'Task Manager' - alternatively it can be accessed from the lock screen (Ctrl-Alt-Delete)
When opening Task Manager for the first time it might look like this:
In order to use the full functionality, click on the 'more details' option - which will look like this:
This displays a list of applications and processes, along with the amount of CPU and Memory each process is currently using on the machine.
If there are performance issues, click the 'CPU' column to sort by processes using the most compute power - from here the problematic application can be closed and reopened (end task).
The 'Performance' tab at the top displays a timeline graph of the device's performance, and also provides the last boot up time.
As seen above, the machine hasn't restarted in 2 weeks, which is a long time for it to be running without a restart.
The 'Startup' tab at the top displays all applications that try to automatically launch as soon as the device is turned on.
In the above screenshot there is a lot of applications disabled from starting on startup. This will help increase the machine's performance, as the user can open those applications on a need to use basis, and the applications won't be taking unnecessary compute power from the get go.
The above steps are useful tools to help with general troubleshooting and gathering further information around common PC issues.