A call to action (otherwise known as a CTA) is a clear message of what your readers should do next, such as contact you, click through to your website, or schedule an appointment.
CTAs included in print material, such as leaflets and magazines - are typically accompanied by a contact number, email address or website address that helps the reader complete the required action.
Digital CTAs, for example on websites or in emails - should include a hyperlink that redirects the reader to help them perform the required action, for example a contact page or an email address.