Callout extensions are a really important component of Google AdWords, and they can be incredibly useful in describing what your business has to offer that may not be clear by your links and description alone. Take the example below from Google: “Acme Electronics” uses AdWords and is able to list their website in the first line, general business description in the second line, and then the third line offers three “call-out” phrases where they can let users know about special services they offer which set them apart from the competition. It is a non-clickable addition to your listing, similar to rich snippets