Variation, i.e. the molecular and phenotypic changes caused by random mutations, is a crucial component of evolutionary processes. One biologically relevant example for which variation can be modelled computationally is the RNA genotype-phenotype (GP) map. This GP map links RNA sequences to their folded secondary structures and thus allows us to identify structural changes after sequence mutations. In this talk, I will describe some recent progress on the biophysics of this GP map, show what the properties of this GP map mean for evolutionary processes, and discuss what we can learn from this GP map for evolutionary processes beyond RNA