In web design and in copywriting, the call to action is designed to get a response and create urgency. The call to action is what tells the visitor exactly what to do next. Think of the Download Now, Click Here, Buy Now, Sign Up Today buttons.
Calls to action are the number one way to drive conversions on a given page. Without them, your traffic has no clue what you want them to do. If you don’t ask them to sign up for a newsletter or download an e-book, they won’t do it.