The document discusses the importance of including a clear call to action in marketing campaigns. It explains that a call to action tells people what action you want them to take, such as purchasing a product by a certain date to receive a discount. Direct response campaigns that include specific calls to action are easier to track and test than general branding campaigns. The document recommends marketers explicitly ask for the sale by including calls to action like "Sale ends Saturday" or "Call before Friday to receive your free gift."