The search for extraterrestrial intelligence (SETI) is a collective term for the scientific search for intelligent extraterrestrial life. For example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other worlds.
Scientific investigation of the potential phenomenon began shortly after the advent of radio in the early 1900s. Focused international efforts to answer a variety of scientific questions have been going on since the 1980s.
There are great challenges in searching the universe for signs of intelligent life, including their identification and interpretation. As various SETI projects have progressed, some have criticized early claims by researchers as being too "euphoric".