Anomalous transport coefficients, which express the H-mode and L-mode in a unified manner, are obtained by use of a theory of self-sustained turbulence. The reduction of transport coefficients and the fluctuations in the H-mode are shown quantitatively. The L-H mode transition condition and the structure of the transport barrier are discussed. The existence of various transport barriers (particle, momentum and heat) is also pointed out. The dynamics of the barrier formation and the relation to ELM are discussed.