  Solving the electronic Schr\"odinger equation for changing nuclear
coordinates provides access to the Born-Oppenheimer potential energy surface.
This surface is the key starting point for almost all theoretical studies of
chemical processes in electronic ground and excited states (including molecular
structure prediction, reaction mechanism elucidation, molecular property
calculations, quantum and molecular dynamics). Electronic structure models aim
at a sufficiently accurate approaximation of this surface. They have therefore
become a cornerstone of theoretical and computational chemistry, molecular
physics, and materials science. In this work, we elaborate on general features
of approximate electronic structure models such as accuracy, transferability,
and general applicability in order to arrive at a perspective for future
developments, of which a vanguard has already arrived. Our quintessential
proposition is that meaningful quantum mechanical predictions for chemical
phenomena require system-specific uncertainty information for each and every
electronic structure calculation, if objective conclusions shall be drawn with
confidence.
