Polyelectrolyte chains confined by macroions bearing electrostatic charges of opposite sign can mediate an effective attraction between the macroions. This polyelectrolyte-mediated attraction is usually referred to as the bridging interaction. I review the theories of polyelectrolyte-mediated interactions based on analytic mean-field and variational approaches. I will describe the origin and the salient properties of this interaction in the context of planar and point macroions with special emphasis on the connection between the polymer chain conformations and the ensuing polymer mediated interactions. (C) 2004 Wiley Periodicals, Inc.