Many sales scripts are designed to move the prospect sequentially through the cognitive, affective and behavioural stages of the purchase decision process and are designed around the AIDA model (attention →interest →desire →action). Most sales representatives include a greeting, closing and call to action in their scripts. A "call to action" (CTA) is simply an instruction to the prospect designed to prompt an immediate response. It often involves the use of an imperative verb such as "try it now" or "find out more." Other types of calls-to-action might provide consumers with strong reasons for purchasing immediately such an offer that is only available for a limited time, e.g. 'Limited stocks available' or a special deal usually accompanied by a time constraint, e.g. 'Order before midnight to receive a free gift with your order'. The key to a powerful call-to-action is to provide consumers with compelling reasons to purchase promptly rather than defer purchase decisions.