Stops script when some step fails. Similar to Shell set -e. Translates to inserting the line '$ErrorActionPreference = "Stop"' into the beginning of your command block. See documentation on ErrorActionPreference.
However, this can break scripts that have advanced parameter blocks, specifically those utilizing '[CmdletBinding()]' in the beginning as this must be the first executable line in a scriptblock, resulting in an 'UnexpectedAttribute' error.