Cloud computing is a service model where data is stored remotely and accessed over the internet. There are three types of clouds - public, private, and hybrid. Public clouds are available to the general public, private clouds are operated solely for an organization, and hybrid clouds combine two or more cloud types. Popular cloud providers include iCloud, Dropbox, Amazon Cloud, and Google Drive which provide free storage and enable access across devices. The advantages of cloud storage are lower costs, online backup, improved performance, and unlimited capacity while disadvantages include reliance on internet and potential security and privacy risks.