E-commerce is defined as financial transactions that are conducted by electronic means. With the growth of commerce on the Internet and the World Wide Web, e-commerce often refers to purchases from online stores, otherwise knows as e-commerce Web sites. They may also be referred to as "virtual-stores" or "cyber stores". An e-business enterprise uses the Internet, intranets, extranets, and other networks to support every step of the commercial process. This might include everything from advertising, sales, and customer support on the Web, to Internet security and payment mechanisms that ensure completion of delivery and payment processes. E-commerce transactions generally fall into one of four business models which are: