Running work in the background or in parallel in PowerShell: Start-Job, ThreadJob, ForEach-Object -Parallel, Start-Process, and runspaces. Use when you need to run commands concurrently, launch a long-running process without blocking, fan out work over many items, wait on / collect background results, or speed up an I/O-bound loop. Notes which mechanisms are 7+ only vs available in 5.1.
