To understand cloud computing, you need to understand the usual way that people store information on computers. For many years, people and businesses would use computers that were located at their home or place of business to store data on or to run special computer programs on. At some point in the early part of the 21st century, new businesses started appearing that offered customers the use of large computers owned by these new businesses. These computers could be used by the customers to store information and programs on. The customers could connect to these computers from wherever they lived or worked, using the Internet, and access the information or use the programs stored on those computers.
Since the actual physical computers were no longer located in the home or office of the customer, they started being described as being “in the cloud," as in “well, they’re somewhere up there in the clouds; I don’t know exactly where...” The cloud is other people running computers on your behalf that you can reach over the Internet.
EXAMPLE: You could take several pictures with your camera and then use a program to get the pictures off your camera and store them in the “cloud." Later on, you could access those pictures using your phone or a computer.