Monotone sets have been introduced about fifteen years ago by Cheeger and Kleiner who reduced the proof of the non biLipschitz embeddability of the Heisenberg group into L1 to the classification of its monotone subsets. Other motivations for the study of monotone sets come from their relationship with minimal hypersurfaces, subharmonic maps, uniform rectifiability. In this talk I will discuss some hints towards a classification of monotone sets in the wider setting of step 2 Carnot groups, with a particular emphasis on cases, beyond the Heisenberg group, where a complete classification can be achieved. Based on joint works with E. Le Donne and D. Morbidelli.