Novel superconducting compounds such as the high T c oxides are intrinsically inhomogeneous systems. An inhomogeneous structure is created by doping and the statistical nature of the distribution of dopants. Consequently, the critical temperature is spatially dependent: T c ≡ T c (r).Pair-breaking leads to a depression of T c and is a major factor leading to inhomogeneity . The "pseudogap" state is characterized by several energy scales : T*, T c *, and T c ≡ T c res. . The highest energy scale (T*) corresponds to the phase separation (at T T > T c : the compound contains superconducting "islands" embedded in the normal metallic matrix. As a result ,the system is characterized by normal conductance along with an energy gap structure, anomalous diamagnetism, unusual a.c. properties, isotope effect, and "giant" Josephson proximity effect. The energy gap may persist to temperature above T c * caused by the presence of a charge density wave (CDW) or spin density wave (SDW) in the region T>T c * by CDW, SDW, etc, whereas below T c * the pairing also makes a contribution to the energy gap (T c * is an "intrinsic" critical temperature). The values of T*, T c *, T c ≡ T c res. depend on the compound and the doping level. The transition at T c into the dissipationless (R=0) macroscopically coherent state is of a percolation nature.