What is a computing cloud, really? It is a large collection of processors, memory, and storage space with access to massive amounts of Internet bandwidth. Working together, a group of computers can be accessed by thousands of simultaneous users to handle tasks. As they are physically located at facilities out on the Internet and not locally at the customer premise, they are considered to be "in the cloud" which is a reference to the way that the Internet has been represented in diagrams for a long time.
Cloud computers are flexible and fast super computers which are now available to anyone with a credit card. A company doesn't have to spend thousands in upfront costs for infrastructure and bandwidth, two hurdles which prohibited their use by the average SMB customer in the past. One of the biggest trends in 2009 was the cheap and easy access to computing power and bandwidth that would have been way out of reach for the average SMB even just 2 years ago. While this business model has been gaining popularity amongst legitimate business customers, the darker side of the Internet contains similar offerings for more sinister applications.