A process implemented by an uninformed party to induce other parties with private information to act so as to reveal it. In equilibrium both the uninformed and the informed are aware of the informational consequences of their actions. In the case where the uninformed party takes the initiative, screening is employed. In the case where the informed takes the initiative to identify himself as a particular type, it is considered to be signalling. Thus the difference between screening and signalling lies in whether the informed or uninformed party moves first. See also asymmetric information.
Reference: Oxford Press Dictonary of Economics, 5th edt.