Euclid is an ESA mission designed to understand the nature of the Dark Energy responsible for the accelerated expansion of the Universe and constrain the nature of Dark Matter. These goals will be achieved by investigating the distance-redshift relationship and the evolution of cosmic structures. Euclid will be equipped with a 1.2 m diameter SiC mirror telescope feeding 2 instruments: the visible imager (VIS) and the Near-Infrared Spectro-Photometer (NISP). In this paper Euclid’s observation probes and main aims are recalled, and the NISP instrument and expected performances are presented.