A significant progress has been made in controlling the properties of the radiation emitted by a FEL amplifier. Experiments have demonstrated both the possibility to increase the temporal coherence and to reduce the amplifier length to reach saturation, by seeding it with an external source. The FERMI seeded Free Electron Laser (FEL) is based on two complementary FEL lines, FEL-1 and FEL-2. FEL-1 is a single stage cascaded FEL delivering light in the 65-20nm wavelength range, while FEL-2 is a double stage cascaded FEL where the additional stage extends the frequency up-conversion to the spectral range of 20-4nm. The main aspects and results achieved with these two beam lines will be briefly reviewed, together with the future possibilities opened by the increased control on the FEL process allowed by the interaction with the external seed.