With the label of Intermediate Luminosity Optical Transients (ILOTS)", I refer to several types of eruptive variables with luminosities intermediate between classical novae (M > -10) and core-collapse supernovae (M < -15). Some ILOTS are believed to be stellar mergers, or unusual sub-luminous supernovae. Others are known to be major outbursts of massive stars (including different classes of super/hypergiants, luminous blue variables and early-type Wolf-Rayet stars), that can mimic the observed parameters of true supernovae, although the star survives the eruptive event. They are usually labelled as "supernova impostors". More interestingly, occasionally, major outbursts are observed a very short time (weeks to a few years) before terminal supernova explosions. I will review some interesting ILOTS, a new powerful tool to link the progenitor stars with the different scenarios of supernova explosions.