PowerShell | Intro | Jobs and More..
Parallel vs Series
This is where you process one request at a time vs multiple. For example a foreach loop does one at a time where a job can run thousands at a time and can greatly reduce the amount of time a PowerShell script takes to execute. These are usually applicable when dealing with large quantities of computer systems. There are multiple cmdlets to assist in running things as Jobs / Runspaces etc…Here is a example on this site using -AsJob and Receive-Job:
Local Group Membership
Services IIS SQL
These are a bit advanced concepts so don't spend tons of time on these if you are just beginning.
Here is a site with some more info: