Definition: An interface element (usually in the form of a button, link, etc) that aims to prompt or encourage a user to perform a particular activity
Thought: The Call To Action should be displayed prominently to guide the user, focus the site, and measure success. Word of warning, less is more! Don't render your perfectly crafted Call To Action useless by offering too many actionable options. Be precise and determined in your placement. You should not take this topic lightly; take action instead!