Founded in 1995, eBay provides an online auction model, with internet users as buyers and sellers and eBay acting as the auction house. One of the advantages that technology was that it is a lot easier to bring together parties interested in very specific sorts of items, that would otherwise find it difficult to find people to sell to or buy from. Therefore, eBay has always been popular with collectors. Arguably, the largest problem eBay has faced has been instilling confidence in its buyers: with sellers pseudonymous, how could eBay guarantee that sellers were entering into contracts with the intention and capability to fulfil them? Previously, this trust was based primarily on a seller’s reputation, which was determined by short reviews (feedback) from previous buyers. Sellers are also able to respond to feedback, thus creating a personal history that allowed prospective buyers to make up their own minds as to whether they wanted to trust the seller. Without the socially mediated trust/relationship structure, it is unlikely that eBay could have grown large enough to be able to guarantee its transactions in the way it can today.
Epinions.com is a general consumer review site that was established in 1999. Epinions was acquired by Shopping.com (known as DealTime.com at the time of the acquisition) in 2003, which in turn was acquired by Ebay in 2005. At Epinions, visitors can read reviews about a variety of items to help them decide on a purchase or they can join for free and begin writing reviews that may earn them money and recognition, according to the site's FAQs .  (via wikipedia )