N6-methyladenosine (m6A) is the most abundant internal modification in eukaryotic mRNA. Recent discoveries of the locations, functions and mechanisms of m6A have shed light on a new layer of gene regulation at the RNA level, giving rise to the field of m6A epitranscriptomics. In this Perspective, we provide an update on the various effects of mammalian m6A modification, which affects many different stages of the RNA life cycle.