These transactions are generally conducted through a third party that provides an online platform on which the transactions are carried out.
Online auctions and classified advertisements are two examples of C2C platforms. EBay and Craigslist are two well-known examples of these platforms. Because eBay is a business, this form of e-commerce could also be called C2B2C -- consumer-to-business-to-consumer. Platforms like Facebook marketplace and Depop -- a fashion reselling platform -- also enable C2C transactions.