  A general thermodynamic framework is presented for open quantum systems in
fixed contact with a thermal reservoir. The first and second law are obtained
for arbitrary system-reservoir coupling strengths, and including both
factorized and correlated initial conditions. The thermodynamic properties are
adapted to the generally strong coupling regime, approaching the ones defined
for equilibrium, and their standard weak-coupling counterparts as appropriate
limits. Moreover, they can be inferred from measurements involving only system
observables. Finally, a thermodynamic signature of non-Markovianity is
formulated in the form of a negative entropy production rate.
