Technosignatures: Methods, Challenges, and Prospects in the Search for Intelligent Extraterrestrial Life

To the point

Technosignatures are signs of intelligent extraterrestrial technology that go beyond finding planets, such as signals, large-scale structures, chemical pollutants, and unusual energy use, and they are searched for by Frank Drake via Project Ozma and by programs like Breakthrough Listen, METI, and SETI@home using radio, optical, infrared, and transit observations to detect alien civilizations and to rethink habitable zones.