A Buying group, also known as collective buying, is a group of noncompeting retailer s that analyze, select, and purchase products and services together, such as advertising and equipment. The buying group offers products and services at significantly reduced prices on the condition that a minimum number of buyers would make the purchase. Generally, websites will feature a "deal of the day", with the deal kicking in when a set number of people agree to buy the product or service. buyers then print off a voucher to claim their discount at the retailer.

Source: www.subicom.com