What "cloud" really means is using Internet services for file sharing, email, document sharing, etc. Rather than storing files on your local network, the files get stored back up on the remote server. The remote server is maintained by the cloud services company. Email has been used this way for years: you purchase email hosting on a monthly basis and never think about the server housing its contents. All of that server side storage is done remotely through an Internet connection. Cloud services are generally cheaper and the costs to implement and maintain are much lower than housing your own internal server.