  Non-Hermitian photonic lattices combine the peculiar consequences of energy
non-conservation with the physics of bandstructures, giving rise to a variety
of exotic properties not found in conventional materials or photonic
metamaterials. In this tutorial, we introduce the key concepts in the design
and implementation of non-Hermitian photonic lattices, including the general
features of non-Hermitian lattice Hamiltonians and their bandstructures, the
role of non-Hermitian lattice symmetries, and the topological chracterization
of non-Hermitian bandstructures. We survey several important non-Hermitian
lattice designs, as well as the photonic platforms on which they can be
realized. Finally, we discuss the possibilities for future developments in the
field.
