Cloud computing is the delivery of services over the Internet. It delivers computing resources such as servers, software or applications, etc. over the internet. All of these services are provided over the Internet rather than using these services on your personal computer or local servers.
You can consider cloud computing as a big hard drive that you don't need to manage or own by yourself. You can just use these services over the Internet. For example, when you are using services like Google Drive or Netflix to watch movies, you are using cloud computing.
There are different types of cloud
Example - Amazon Web Services (AWS) and Google Cloud Platform (GCP)
Example - VMware private cloud, Microsoft Azure cloud
Example -> Integrating a private cloud with AWS
There is no such thing as a protected cloud, and other different types of clouds are community clouds and multi-clouds, but there is no protected cloud.