  Co-orbital exoplanets are a by-product of the models of formation of
planetary systems. However, none have been detected in nature thus far.
Although challenging, the observation of co-orbital exoplanets would provide
valuable information on the formation of planetary systems as well as on the
interactions between planets and their host star. After a brief review of the
stability and formation issues of co-orbital systems, some observational
methods dedicated to their detection are presented.
