Two-dimensional systems (2D) are a 'pure surface', and its properties can be adjusted by modulating its environment. For instance, depositing a 2D system over different substrates, stacking them in heterostructures, adding a twist angle between different layers, or depositing molecules 
onto it. In this talk, we will discuss all these examples through nano-Raman spectroscopy. Such environmental perturbations cause phonon and electron localization at a nanometer scale; the consequences and effects of such perturbations on the 2D systems are then understood through their atomic modelling.