In 2012 Gaiotto introduced special conformal defects (or domain walls) between a UV and IR fixed point CFTs. These defects, to which we refer as RG defects, are meant to produce an expansion of local fields at an infrared fixed point in terms of the local fields at the UV fixed point. We discuss Gaiotto's ideas, in particular - their relation to perturbation defects considered by Brunner and Roggenkamp. We also generalize Gaotto's defects to pure boundary RG flows in two dimensions. For perturbative flows between boundary conditions in minimal models we propose a particular boundary condition changing field that is conjectured to play the role of RG defect.
