  A simple derivation of the bound on entropy is given and the holographic
principle is discussed. We estimate the number of quantum states inside space
region on the base of uncertainty relation. The result is compared with the
Bekenstein formula for entropy bound, which was initially derived from the
generalized second law of thermodynamics for black holes. The holographic
principle states that the entropy inside a region is bounded by the area of the
boundary of that region. This principle can be called the kinematical
holographic principle. We argue that it can be derived from the dynamical
holographic principle which states that the dynamics of a system in a region
should be described by a system which lives on the boundary of the region. This
last principle can be valid in general relativity because the ADM hamiltonian
reduces to the surface term.
