Business to Business
This is Business to Business transactions. Here the companies are doing business with each other. The final consumer95 is not involved. So the online transactions only involve the manufacturers, wholesalers, retailers91 etc.
2. Business to Consumer
Business91 to Consumer. Here the company will sell their goods and/or services directly to the consumer. The consumer can browse their websites and look at products, pictures, read reviews. Then they place their order and the company ships the goods directly to them. Popular examples are Amazon, Flipkart, Jabong etc.
Consumer to Consumer
Consumer to consumer, where the consumers are in direct contact with each other. No company is involved. It helps people sell their personal goods and assets directly to an interested party. Usually, goods traded are cars, bikes, electronics etc. OLX, Quikr etc follow this model.
4. Consumer to Business
This is the reverse of B2C, it is a consumer to business. So the consumer provides a good or some service to the company91. Say for example an IT freelancer who demos and sells his software to a company. This would be a C2B transaction.