In business usually consists of three types: production, distribution or retail. Owners and business management will select one or more options from the three species. Production can be broken and then sell to distributors, or a true sale to retail, and others.
As Internet technology is used to do business, some kind of efficiency of business processes start to happen. Amazon cut off the distributor and / or retail. Through online, they can reach the target consumer orders a book without having to have the inventory / stock.
Amazon as a huge online mall, online bookstore again instead of electronics and others.
There are still many ways that was later found, after gradually emerging Internet applications.
With the social networking, how marketing is changing. Still in the context of production-distribution-retail, retail-emerging online retail on the internet. Must not have their own web pages, online store account was enough. And this can be done without having an actual offline store, the factory that actually, even the actual distributor.
Third, for many large companies that produce thousands to millions of products with a particular brand, entering the online world is their next choice.