Cloud

In IT, the term "cloud" is used to define servers that can be accessed over the Internet, and the software and databases that run on those servers.

"Cloud computing" is a term used to define specific client-server computing architecture. It is based on virtualization technology and enables users to reach applications and files without being bound to a specific device. For example, one can reach their account in Facebook using different cell phones or tablets. Though users are expected to pay for using cloud services, they have a chance of reducing their expenses as there is no more need to manage physical servers and machines.

Depending on the components hosted on cloud servers and used by cloud users, there are several main service models of cloud computing:

SAAS. Cloud users are provided with access to applications hosted on cloud servers. Examples: Salesforce, Gmail.

PAAS. Cloud users are provided with everything needed to develop their own applications (i.e. cloud-hosted development tools, operating systems, infrastructure). Example: Microsoft Azure.

IAAS. Cloud users are provided with servers and storage hosted on the cloud. This infrastructure is used by them to develop their own applications while they use their own development tools and operating system. Example: OpenStack.

It should also be noted that in case of cloud computing, a VM can either share the resources or have dedicated ones depending on the cloud providers’ policy and the VM’s user requirements.