  Motivated by the understanding of holography as realized in tensor networks,
we develop a bulk procedure that can be interpreted as generating a sequence of
coarse-grained holographic states. The coarse-graining procedure involves
identifying degrees of freedom entangled at short distances and disentangling
them. This is manifested in the bulk by a flow equation that generates a
codimension-1 object, which we refer to as the holographic slice. We generalize
the earlier classical construction to include bulk quantum corrections, which
naturally involves the generalized entropy as a measure of the number of
relevant boundary degrees of freedom. The semiclassical coarse-graining results
in a flow that approaches quantum extremal surfaces such as entanglement
islands that have appeared in discussions of the black hole information
paradox. We also discuss the relation of the present picture to the view that
the holographic dictionary works as quantum error correction.
