An overlay page allows you to display a small non-intrusive overlay on the destination website to advertise your product or your services. You can also use this feature to send a message to your users. You can customize the message and the appearance of the overlay right from this page. As soon as you save it, the changes will be applied immediately across all your URLs using this type.
Please note that some secured and sensitive websites such as google.com, twitter.com or facebook.com do not work with this feature due to security protocol.