  In this work, we classify the group gradings on finite-dimensional incidence
algebras over a field, where the field has characteristic zero, or the
characteristic is greater than the dimension of the algebra, or the grading
group is abelian.
  Moreover, we investigate the structure of $G$-graded $(D_1,D_2)$-bimodules,
where $G$ is an abelian group, and $D_1$ and $D_2$ are the group algebra of
finite subgroups of $G$. As a consequence, we can provide a more profound
structure result concerning the group gradings on the incidence algebras, and
we can classify their isomorphism classes of group gradings.
