Admit it. Be honest now. We've all done it. We've run a command against a batch of users and forgot to limit the scope to the ones we were really targeting.
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Some environments have multiple domains in a single Active Directory forest. Working with Powershell in the same domain as your user account is easy, but what do you do when you need to run Powershell commands in one of the other domains? Change context. Powershell can traverse AD as a file system, and this allows an easy way to change the context for your script. Keep in mind, that to be able to load the AD Powershell module, you need to install the RSAT tools on the workstation that you are using to run your commands.