  We review the main results and ideas showing that quantum correlations at
finite temperatures (T), in particular quantum discord, are useful tools in
characterizing quantum phase transitions that only occur, in principle, at the
unattainable absolute zero temperature. We first review some interesting
results about the behavior of thermal quantum discord for small spin-1/2 chains
and show that they already give us important hints of the infinite chain
behavior. We then study in detail and in the thermodynamic limit (infinite
chains) the thermal quantum correlations for the XXZ and XY models, where one
can clearly appreciate that the behavior of thermal quantum discord at finite T
is a useful tool to spotlight the critical point of a quantum phase transition.
