Whereas the Solar System has Mars and Europa as the best candidates for
finding fossil/extant life as we know it - based on complex carbon compounds
and liquid water - the 263 (non-pulsar) planetary systems around other stars as
known at 15 September 2008 could between them possess many more planets where
life might exist. Moreover, the number of these exoplanetary systems is growing
steadily, and with this growth there is an increase in the number of planets
that could bear carbon-liquid water life. In this brief review the main methods
by which exoplanets are being discovered are outlined, and then the discoveries
that have so far been made are presented. Habitability is then discussed, and
an outline presented of how a planet could be studied from afar to determine
whether it is habitable, and whether it is indeed inhabited. This review is
aimed at the astrobiology community, which spans many disciplines, few of which
involve exoplanets. It is therefore at a basic level and concentrates on the
major topics.Comment: 37 pages, 12 Figure
