Transfer RNA-derived small RNAs (tsRNAs) are an emerging class of regulatory non-coding RNAs that play important roles in post-transcriptional regulation across a variety of biological processes. Here. we review the recent advances in tsRNA biogenesis and regulatory functions from the perspectives of functional and evolutionary genomics. with a focus on the tsRNA biology of Drosophila. https://www.drcristinosuarez.com/