SETI, or the Search for Extraterrestrial Intelligence, is a scientific effort seeking to determine if there is intelligent life outside Earth. SETI researchers use many methods. One popular method, radio SETI, listens for artificial radio signals coming from other stars. SETI@home is a radio SETI project that lets anyone with a computer and an Internet connection participate.
Radio telescope signals consist primarily of noise (from celestial sources and the receiver's electronics) and man-made signals such as TV stations, radar, and satellites. Modern radio SETI projects analyze the data digitally. More computing power enables searches to cover greater frequency ranges with more sensitivity. Radio SETI, therefore, has an insatiable appetite for computing power.
Previous radio SETI projects have used special-purpose supercomputers, located at the telescope, to do the bulk of the data analysis. In 1995, David Gedye proposed doing radio SETI using a virtual supercomputer composed of large numbers of Internet-connected computers, and he organized the SETI@home project to explore this idea. SETI@home was originally launched in May 1999.
The SETI@home project hopes to convince you to allow us to borrow your computer when you aren't using it and to help us "…search out new life and new civilizations." We'll do this with a screen saver that can go get a chunk of data from us over the internet, analyze that data, and then report the results back to us. When you need your computer back, our screen saver instantly gets out of the way and only continues it's analysis when you are finished with your work.
As seen in Chapter 5 of Citizen Science by Caren Cooper.