I keep seeing references to UV and IR in references to string theory and quantum gravity. This seems to come up in discussions of renormalization especially. Can someone please explicitly explain the term? Google doesn't seem to help here. There are way too many references. I have tried various combinations with other terms as well but haven't found anything useful yet. I know that UV means ultraviolet and IR means infrared but this does not really help as the meaning clearly has more specificity when used in the context of quantum gravity than just a reference to small bands in the EM spectrum. It seems as if the terms mean the quantum scale and cosmological scale at times based on context. Is this close?