  A scenario which can account for all observed features of both high-$T_c$
superconductors (HTS) and low-$T_c$ superconductors (LTS) is discussed. This
scenario is based on the fact that a finite pairing interaction energy range
$T_d$ is required to have a finite value of $T_c$ and that not all carriers
participate in pairings, yielding multiconnected superconductors (MS). A new
density of states, derived by keeping the order parameter zero outside of
$T_d$, is shown to account for the observed low energy states in HTS and for
the temperature dependences in the specific heat, the penetration depth, the
optical conductivity, and the tunneling conductance data. I argue that the
notion of MS can account for the tunneling data along the a(or b)-, ab-, and
c-axis, and the 1/2 flux quantum observed in HTS. The region occupied by
unpaired carriers can be considered as a vortex with a fluxoid quantum number
equal to 1 (VF), 0 (VZF), or -1 (VAF) when the magnetic flux around the vortex
is greater than, equal to, or less than the effective flux produced by the
supercurrent, respectively. The Hall anomaly depends on the relative strengths
of the contributions via VF and VAF. The fact that the present scenario can
account for all observed features of HTS and LTS suggests that the symmetry of
the order parameter in HTS may not be different from one in LTS.
