  Quantum thermodynamics and quantum information are two frameworks for
employing quantum mechanical systems for practical tasks, exploiting genuine
quantum features to obtain advantages with respect to classical
implementations. While appearing disconnected at first, the main resources of
these frameworks, work and correlations, have a complicated yet interesting
relationship that we examine here. We review the role of correlations in
quantum thermodynamics, with a particular focus on the conversion of work into
correlations. We provide new insights into the fundamental work cost of
correlations and the existence of optimally correlating unitaries, and discuss
relevant open problems.
