A call to action (CTA) is a prompt on a website that tells the user to take some specified action. A call to action is typically written as a command or action phrase, such as 'Sign Up' or 'Buy Now and generally takes the form of a button or hyperlink.
Your message's call to action is the section that instructs your audience on what to do. If stated properly, it also gives them the motivation to carry it out.
It's the portion of the commercial in marketing that aims to convert viewers into customers, or, in marketing jargon, to increase your conversion rate.
In other fields, the objective can be to persuade someone to read anything you wrote or to do something else. For illustration,
read this book.
A call to action instructs a person to take action. Well-designed things compel people to want to do the same thing.