The search for extraterrestrial intelligence (SETI) is the collective name for a number of activities people undertake to search for intelligent extraterrestrial life. SETI projects use scientific methods in this search. For example, electromagnetic radiation is monitored for signs of transmissions from civilizations on other worlds. Some of the most well known projects are run by Harvard University, the University of California, Berkeley and the SETI Institute. Since the United States government withdrew funding for SETI projects in 1995, projects have been primarily funded by private sources.
There are great challenges in searching the cosmos for signs of intelligent life, including their identification and interpretation. SETI projects necessarily make assumptions to narrow the search, the foremost being that electromagnetic radiation would be a medium of communication for advanced extraterrestrial life.