  The paper emphasizes the property of stability for skew-evolution semiflows
on Banach spaces, defined by means of evolution semiflows and evolution
cocycles and which generalize the concept introduced by us in a previous paper.
There are presented several general characterizations of this asymptotic
property out of which can be deduced well known results of the stability
theory. A unified treatment in the uniform and in the nonuniform setting is
given. The main results are also formulated in discrete time.
