In this paper we review a number of recent developments in the study of the
Discrete Nonlinear Schrodinger (DNLS) equation. Results concerning ground
and excited states, their construction, stability and bifurcations are pres
ented in one and two spatial dimensions. Combinations of such steady states
lead to the study of coherent structure bound states. A special case of su
ch structures axe the so-called twisted modes and their two-dimensional dis
crete vortex generalization. The ideas oil such multi-coherent structures a
nd their interactions are also useful in treating finite system effects thr
ough the image method. The statistical mechanics of the system is also anal
yzed and the partition function calculated in one spatial dimension using t
he transfer integral method. Finally, a number of open problems and future
directions in the field are proposed.