A call-to-action (CTA) is a request to perform an action that triggers an immediate reaction. In many cases this is, for example, to conclude a purchase contract or to be redirected to a Website. In marketing campaigns, the call-to-action also plays a major role when it comes to prompts, for example, where a comment is to be written under a post or certain reactions to a video are expected. Participation in a competition is also a CTA.