The term 'BIDDER'S SITE' can be summarized as an online marketplace where buyers and sellers can interact. The most popular example of this is eBay, which is a four-letter word that fits the crossword puzzle. eBay is an American multinational e-commerce corporation based in San Jose, California, that facilitates consumer-to-consumer and business-to-consumer sales through its website. It allows users to buy and sell a wide variety of goods and services worldwide.