What is a call for action?

What is a call for action?

The Title and META-Description is used by some search engines to present a summary of the web page along with the Link to the page.
The search result will look like this:
Your web page title
Meta-tag description
Link to your site

So this could be:
Fishing trips Alaska
Visit our site to see how to enjoy a great fishing trip to Alaska. Ever cached a salmon in front of a ice-mountain?

Be sure to call the Visitor to take action. This can increase "CTR" dramaticly.