Transverse momentum dependent functions (TMDs) are an essential component of the rich phenomenology in hadronic processes. Recent data and phenomenological analyses have allowed us, on one hand, to explore some of the features of these non-perturbative functions. On the other, they have also made it evident that several theoretical issues remain to be understood towards a fully QCD-consistent determination of TMDs. In this talk, I will provide my view of these issues and will outline some of the relevant recent and ongoing work that aims at their resolution.