What is a corporate structure in the United States whereby the owners are not personally liable for the company's debts or liabilities?

Commercial enterprise that dedicates itself to buying already made products and reselling them to make profit?

This business takes raw materials and mass produces goods. Usually it uses robots, computers, assembly lines, and human labor to make goods.

What kind of business specializes in performing services for the consumers?

What business is a combination of the traditional business firms and the internet? These businesses not only specialize in traditional methods of distribution, but also ways using different technology.