The concept of work in thermodynamics is well known and can be well defined in a process in which a property of the system (the position of a piston, the strength of a field) changes from an initial to a final value.In quantum mechanics it has been recently realised that work cannot be associated with the expectation value of an observable but rather with the transition probabilities between energy eigenstates [1]. As a consequence, only the work probability distribution can be properly defined for a given process. In this seminar I will first revise the recent developments concerning the definition of work in quantum mechanics. Then I will discuss a proposal, based on Ramsey interferometry, for measuring the work probability distribution without the need of energy measurements before and after the process. This scheme has recently been implemented in an NMR setting successfully verifying two fundamental relations in thermodynamics, Tasaki-Crooks and Jarzynski relations [3].Finally, I will mention the latest developments on the work distribution for many-body systems, in particular for 1D spin chains, and its relation to equilibrium properties. [1] M. Campisi, P. Haenggi and P. Talkner, Rev. Mod. Phys. 83, 771 (2011).[2] L. Mazzola, G. De Chiara and M. Paternostro, Phys. Rev. Lett. 110, 230602 (2013), arxiv:1401.0566[3] T. Batalhao, A. M. Souza, L. Mazzola, R. Auccaise, I. S. Oliveira, J. Goold, G. De Chiara, M. Paternostro, R. M. Serra, arxiv:1308.3241