  Dislocation model of the supersolid state of $^4$He was proposed in 1987 by
one of the authors of the review. The model obtained strong support by numerous
experimental and theoretical investigations from 2007 to date. In these
investigations the validity of the idea put forward in 1987 was confirmed, and
new conceptions of superclimb of dislocations and of the giant isochoric
compressibility or the syringe effect were proposed. In this paper we review
main achievements of theoretical and experimental studies of
dislocation-induced supersolid and present current understanding of this
phenomenon.
