  In this chapter we offer an introduction to weak values from a three-fold
perspective: first, outlining the protocols that enable their experimental
determination; next, deriving their correlates in the quantum formalism and,
finally, discussing their ontological significance according to different
quantum theories or interpretations. We argue that weak values have predictive
power and provide novel ways to characterise quantum systems. We show that this
holds true regardless of ongoing ontological disputes. And, still, we contend
that certain "hidden" variables theories like Bohmian mechanics constitute very
valuable heuristic tools for identifying informative weak values or functions
thereof. To illustrate these points, we present a case study concerning quantum
thermalization. We show that certain weak values, singled out by Bohmian
mechanics as physically relevant, play a crucial role in elucidating the
thermalization time of certain systems, whereas standard expectation values are
"blind" to the onset of thermalization.
