Heavy flavours, such as beauty and charm, are a window on the two mechanisms that provide ordinary matter with mass: electroweak symmetry breaking and the binding energy of strong interaction. Indeed, on the one hand, they play a crucial role in studies of the Higgs boson and, on the other hand, they constitute a bridge between perturbative and non-perturbative Quantum Chromo Dynamics (QCD). In this talk, I discuss jet substructure observables that can probe heavy-flavour properties, such as their fragmentation, focussing on jets that have been tagged as heavy-flavoured.