E-commerce refers to buying and selling of goods or services over the internet. It is a subset of e-business, which encompasses all business conducted online. There are several models of e-commerce including B2B, B2C, C2C, C2B, B2G, and G2B. E-commerce has developed in three waves since 1995, driven by improvements in internet technologies, the rise of mobile devices and social media, and greater participation of small businesses online.