  We study the structure of topological phases and their boundaries in the
Projected Entangled Pair States (PEPS) formalism. We show how topological order
in a system can be identified from the structure of the PEPS transfer operator,
and subsequently use these findings to analyze the structure of the boundary
Hamiltonian, acting on the bond variables, which reflects the entanglement
properties of the system. We find that in a topological phase, the boundary
Hamiltonian consists of two parts: A universal non-local part which encodes the
nature of the topological phase, and a non-universal part which is local and
inherits the symmetries of the topological model, which helps to infer the
structure of the boundary Hamiltonian and thus possibly of the physical edge
modes.
