Snippets are script templates. For example a "do-until" or "for" loop or a template for a cmdlet.
By selecting a snippet, the sample code is inserted into the editor. Powershell ISE, see also: how to create a PowerShell script

Calling snippets

Calling snippets is done in the Powershell ISE with Ctrl + J

loads the template into the ISE script area:

Create Snippet yourself

To do this, the script is marked with @' at the beginning and '@ at the end and stored in a variable:

The command "New-ISESnippet" saves the script as a new snippet

Ctrl+J loads our self-created snippet: