  The problem of which Gauss diagram can be realized by plane curves is an old
one and has been solved in several ways. In this paper, we present a direct
approach to this problem. We show that needed conditions for realizability of a
Gauss diagram can be interpreted as follows "the number of exits = the number
of entrances" and the sufficient condition is based on Jordan curve Theorem. We
give a matrix approach of realization of Gauss diagrams and then we present an
algorithm to construct meanders
