Current experimental methods to produce multiphoton corelations will
be reviewed, as well as (theoretical) tools to detect their
non-classicality. Communication complexity problems will be presented
as an application of such phenomena. Quantum solutions for such
problems can beat classical limits. Despite the fact that these
classical limits for some problems take form of Bell inequalities, it
will be shown that there exists quantum solutions which do not involve
entanglement. Technical problems of solutions with entanglement will
be discussed. Links to other quantum information problems will be
presented.
