At the most basic level, a cloud is a collection of computer systems that look like one to you no matter where they are located. Most major cloud computing services provide seamless access to computing platforms that use multiple data centers. 

These data centers are often miles apart and can even be located in different countries and even on different continents.

Cloud computing services are intended to allow customers to quickly increase or decrease their computer usage and thereby charge fees. Many companies, especially those in retail, have much higher computing requirements at certain times of the year.

To meet this need, businesses need a lot of computing power to be inactive for most of the year or to provide computers for short periods of time.

Cloud services allow companies to take advantage of the provider's immense computing power, but only pay for what they use. At a time of increasing demand, cloud service providers allow their customers to meet this demand but consume less for the rest of the year.

Most companies that use cloud service providers have access to them via the Internet or a leased line connection to a data center. 

This allows employees and customers to access cloud applications from anywhere in the world. However, unlike applications that you install on your local computer or server, any disruption to your network can affect access to applications and affect performance. 

Backup and other standard data center services are part of a cloud provider's plans. Make sure you review all contracts to get the level of service you need.