  The close analogy between cluster percolation and string proliferation in the
context of critical phenomena is studied. Like clusters in percolation theory,
closed strings, which can be either finite-temperature worldlines or
topological line defects, are described by a distribution parametrized by only
two exponents. On approaching the critical point, the string tension vanishes,
and the loops proliferate thereby signalling the onset of Bose-Einstein
condensation (in case of worldlines) or the disordering of the ordered state
(in case of vortices). The ideal Bose gas with modified energy spectrum is used
as a stepping stone to derive general expressions for the critical exponents in
terms of the two exponents parameterizing the loop distribution near
criticality.
