Recent years have brought a substantial improvement in the precision of cross section predictions for top-quark pair production at hadron colliders. I will discuss the dominant physical effects involved in this process and the related resummations: soft-gluon, non-relativistic, transverse momentum and boosted-regime. Subsequently, I will concentrate on fixed-order perturbation theory at the next-to-next-to-leading order. In particular, I will discuss a recent calculation at the differential level with emphasis on the choice of scales. Finally, I will review various applications of the results in the light of precision measurements from the LHC and remind of the legacy of the Tevatron.
