  Let K be an algebraically closed, complete nonarchimedean field and let X be
a smooth K-curve. In this paper we elaborate on several aspects of the
structure of the Berkovich analytic space X^an. We define semistable vertex
sets of X^an and their associated skeleta, which are essentially finite metric
graphs embedded in X^an. We prove a folklore theorem which states that
semistable vertex sets of X are in natural bijective correspondence with
semistable models of X, thus showing that our notion of skeleton coincides with
the standard definition of Berkovich. We use the skeletal theory to define a
canonical metric on H(X^an) := X^an - X(K), and we give a proof of Thuillier's
nonarchimedean Poincar\'e-Lelong formula in this language using results of
Bosch and L\"utkebohmert.
