SETI is the scientific search for extraterrestrial intelligence. Several web sites, maintained by various organizations and individuals, are devoted to this field. The Signatories to the Invitation to ETI find these pages interesting and useful, even though we do not necessarily agree with all of their statements and underlying assumptions.
SETI Publications and Organizations -- these sites provide a wide-ranging wealth of information and opinion on radio and optical SETI (the search for an artificial radio signal or pulsed laser signal from many light-years away):
Astrobiology Sites -- Recently there has been a surge of interest in astrobiology, the search for evidence of microbes and other life in the universe. Interest has been evident in the USA, the United Kingdom, and other countries. Excellent websites are provided by:
Extraterrestrial Visitors -- If you consider the possibility that extraterrestrials visited Earth thousands of years ago (ancient astronauts, paleo-SETI, etc.), or more recently (UFOs), you might be interested in these sites: