B2B,B2C AND C2C..

B2B
B2B (business-to-business), also known as e-biz, is the exchange of products, services, or information between businesses rather than between businesses and consumers.
B2C
A transaction that occurs between a company and a consumer, as opposed to a transaction between companies (called B2B). The term may also describe a company that provides goods or services for consumers.
C2C
Consumer-to-consumer (C2C) (or citizen-to-citizen)electronic commerce involves the electronically-facilitated transactions between consumers through some third party. A common example is the online auction, in which a consumer posts an item for sale and other consumers bid to purchase it; the third party generally charges a flat fee or commission. The sites are only intermediaries, just there to match consumers. They do not have to check quality of the products being offered.