"Exploit the urgency and scarcity principle for your site and you'll see conversions increase dramatically". This is one of the most recurrent expressions in the web when talking about marketing strategies, but it could not be truer. If users realise that their time to make a decision is limited or that the product they are interested in is available only in a limited amount of items, they will decide sooner and quicker to purchase. That's exactly what a countdown makes.