Cloud hosting is where your website is hosted on a cluster of servers instead of having your site hosted on one server. In case of an issue, your site can be migrated to another server. Based on the cloud computing technology, it allows numerous machines to work in synchrony as one entity.
Cloud computing is the on-demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet.