Some people wanted things, other people had things and wanted to sell them. The use of classifieds is referred to as classified advertisement.
For example, e Bay Motors serves the automotive marketplace, including vehicles, parts and accessories; and (now closed) was focused on providing a fixed-price trading environment, initially for books music, videos and video games.
This facilitates easy exploration for buyers and enables the sellers to immediately list an item for sale within minutes of registering.
When an item is listed on a C2C site, a nonrefundable insertion fee is charged based on the seller's opening bid on the item.
They do not have to check quality of the products being offered.
Consumer to consumer (C2C) marketing is the creation of a product or service with the specific promotional strategy being for consumers to share that product or service with others as brand advocates based on the value of the product.