What is the difference between on-premises data centers and cloud computing?

Data Centers and Cloud Computing

1. What is a data center?
2. What is the difference between on-premises data centers and cloud computing?
3. What is an SDDC?
4. What are the advantages of using an SDDC?
5. How can cloud computing solve the problems of managing software licenses?
6. What factors should be considered when selecting a cloud vendor or provider?
7. When are private clouds used instead of public clouds?
8. Explain three issues that need to be addressed when moving to cloud computing or services.