  We investigate the phase structure of lattice QCD for general number of
flavors $N_F$. Based on numerical data combined with the results of the
perturbation theory we propose the following picture: When $N_F \ge 17$, there
is only one IR fixed point at vanishing gauge coupling, i.e., the theory in the
continuum limit is trivial. On the other hand, when $16 \ge N_F \ge 7$, there
is a non-trivial fixed point. Therefore, the theory is non-trivial with
anomalous dimensions, however, without quark confinement. Theories which
satisfy both quark confinement and spontaneous chiral symmetry breaking in the
continuum limit exist only for $N_F \le 6$.
