A call-to-action is a piece of instructive content or button intended to prompt your traffic to take the action of signing up to your dating site immediately.
Your call-to-action will usually be an instructive line of copy, for example 'Signup For Free Today' above the registration form, or alternatively an interactive button stating 'Join Now' directing traffic to the registration form.
Call-to-actions should be eye-catching, clear and concise.
They will urge the users to take action. In this case the action should be to register for your dating site.