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% density functional theory performs quite well, providing total energies that  % are accurate to within 50meV.  For weakly correlated materials, DFT has become the underlying workhorse of the scientific community. Crucially, DFT provides the total energy of a given configuration of atoms, enabling the  Combined with the development of algorithms for  The maturity of its various software implementations means researchers can routinely compute know only  the approximate atomic coordinates of a new compound, and compute its optimized structure and myriad of electronic properties. Combined with growing databases of experimental [ICSD] and computed data [MatProj, AFLOW, NIMS], the field of weakly correlated systems has advanced to the point where one can successfully design materials~\cite{Fennie_2008, Gautier_2015, Fredeman_2011}. A clear example that theoretical approaches are coming of age is the recent prediction of superconductivity in H$_3$S under pressure at XXX~K. Indeed, hydrogen sulfide was recently observed to superconduct near 200 K, the highest temperature superconductor discovered so far. In order to understand the challenges particular to correlations in materials design, we need to better define what we mean by a correlated material, which we do in Section~\ref{sec:correlations}.