 It was first introduced by John Hammersley and Dominic Welsh in 1965 as a model of fluid flow in a porous media.It is part of percolation theory, and classical Bernoulli percolation can be viewed as a subset of first passage percolation.Most of the beauty of the model lies in its simple definition (as a random metric space) and the property that several of its fascinating conjectures do not require much effort to be stated.