  We propose a refinement of the physical picture describing different vacua in
bosonic string theory. The vacua with closed strings and open strings are
connected by the string field theory version of the Higgs mechanism,
generalizing the Higgs mechanism of an abelian gauge field interacting with a
complex scalar. In accordance with Sen's conjecture, the condensation of the
tachyon is an essential part of the story. We consider this phenomenon from the
point of view of both a world-sheet sigma-model and the target-space theory. In
the Appendix the relevant remarks regarding the choice of the coordinates in
the background independent open string field theory are given.
