The majority of SETI efforts search for radio signals, but a number of programs search for light pulse or band signals. Today, SETI is primarily sponsored by two organizations, The Planetary Society and the SETI Institute. The Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations, based in Berkeley, California. The detection of another civilization would be one of the most important discoveries in the history of humanity. Even if we cannot understand their signals, the mere fact that we have detected alien beings will probably make it more difficult for humans beings to hate because of physical and cultural differences.
Radio signals travel throughout most of our Milky Way galaxy with very little interference.
They even pass through thick clouds of dust that prevent us from seeing many stars. Most scientists who have looked into the problem of communicating between stars believe that radio is the easiest and cheapest way to search. But most SETI projects have looked for radio signals. It's entirely possible that there is some unknown method of communicating, and that radio may seem as primitive to aliens as smoke signals do to most of us today. However, we can only use the technology we know.