The four main types of ecommerce are business-to-business (B2B), business-to-consumer (B2C), consumer-to-consumer (C2C), and consumer-to-business (C2B).
B2B ecommerce is when businesses sell products or services to other businesses. An example of this would be a wholesale company selling products to a retailer.
B2C ecommerce is when businesses sell products or services to consumers. An example of this would be an online store selling products to customers.
C2C ecommerce is when consumers sell products or services to other consumers. An example of this would be someone selling a used item on eBay.
C2B ecommerce is when consumers sell products or services to businesses. An example of this would be a freelancer selling their services to a company.