Information Technology

There is an increasingly prominent trend in many organizations to move a substantial portion of or even all information technology (IT) operations to an Internet-connected infrastructure known as enterprise cloud computing. As we know, with every technology there are security considerations. For this discussion, please provide a thorough response to the below questions.
Define cloud computing.
List and briefly define three cloud service models.
What is the cloud computing reference architecture?
Describe some of the main cloud-specific security threats