The definition for the cloud can seem murky, but essentially, it’s a term used to describe a global network of servers, each with a unique function. The cloud is not a physical entity, but instead is a vast network of remote servers around the globe which are hooked together and meant to operate as a single ecosystem. These servers are designed to either store and manage data, run applications, or deliver content or a service such as streaming videos, web mail, office productivity software, or social media. Instead of accessing files and data from a local or personal computer, you are accessing them online from any Internet-capable device—the information will be available anywhere you go and anytime you need it.

Businesses use four different methods to deploy cloud resources. There is a public cloud that shares resources and offers services to the public over the Internet, a private cloud that isn’t shared and offers services over a private internal network typically hosted on-premises, a hybrid cloud that shares services between public and private clouds depending on their purpose, and a community cloud that shares resources only between organizations, such as with government institutions.

Source: https://azure.microsoft.com/en-us/resources/cloud-computing-dictionary/what-is-the-cloud