Proper control of the transcriptome is key for diverse aspects of gene expression, cellular functions and development, and its disruption can result in disease. A rapidly accumulating wealth of studies are identifying and functionally characterizing diverse types of RNA base modifications in protein-coding and non-coding RNAs, which have energized the emerging field of 'epitranscriptomics'. In this Viewpoint article, five experts discuss our latest understanding of RNA modifications, including recommendations for best practices and visions for the future.