Abstract
Electronic phase behavior in correlated-electron systems is a fundamental problem of condensed matter physics.
The change in the phase behavior near surfaces and interfaces,
i.e., {\em electronic reconstruction}, is therefore the fundamental issue of the correlated-electron surface or interface science.
In addition to basic science, understanding of such a phase behavior is of crucial importance
for potential devices exploiting the novel properties of the correlated systems.
In this article, we present a general overview of the field,
and then discuss the recent theoretical progress mainly focusing on the correlation effects.
We illustrate the general concept of {\em electronic reconstruction}
by studying model heterostructures consisting of strongly-correlated systems.
Future directions for research are also discussed.
