There are several grid computing systems, though most of them only fit part of the definition of a true grid computing system. Academic and research organization projects account for many of the systems currently in operation. These systems take advantage of unused computer processing power. The most accurate term for such a network is a shared computing system.
The Search for Extraterrestrial Intelligence (SETI) project is one of the earliest grid computing systems to gain popular attention. The mission of the SETI project is to analyze data gathered by radio telescopes in search of evidence for intelligent alien communications. There's far too much information for a single computer to analyze effectively. The SETI project created a program called SETI@home, which networks computers together to form a virtual supercomputer instead.
A similar program is the Folding@home project administered by the Pande Group, a nonprofit institution in Stanford University's chemistry department. The Pande Group is studying proteins. The research includes the way proteins take certain shapes, called folds, and how that relates to what proteins do. Scientists believe that protein "misfolding" could be the cause of diseases like Parkinson's or Alzheimer's. It's possible that by studying proteins, the Pande Group may discover new ways to treat or even cure these diseases.
There are dozens of similar active grid computing projects. Many of these projects aren't persistent, which means that once the respective project's goals are met, the system will dissolve. In some cases, a new, related project could take the place of the completed one.
While each of these projects has its own unique features, in general, the process of participation is the same. A user interested in participating downloads an application from the respective project's Web site. After installation, the application contacts the respective project's control node. The control node sends a chunk of data to the user's computer for analysis. The software analyzes the data, powered by untapped CPU resources. The project's software has a very low resource priority -- if the user needs to activate a program that requires a lot of processing power, the project software shuts down temporarily. Once CPU usage returns to normal, the software begins analyzing data again.
Eventually, the user's computer will complete the requested data analysis. At that time, the project software sends the data back to the control node, which relays it to the proper database. Then the control node sends a new chunk of data to the user's computer, and the cycle repeats itself. If the project attracts enough users, it can complete ambitious goals in a relatively short time span.
As grid computing systems' sophistication increases, we'll see more organizations and corporations create versatile networks. There may even come a day when corporations internetwork with other companies. In that environment, computational problems that seem impossible now may be reduced to a project that lasts a few hours. We'll have to wait and see.
To learn more about grid computing and related topics, take a look at the links on the following page.