Abstract
Recently, non-coding RNAs (ncRNAs) have received a lot of attention in the literature due to their involvement in a plethora of molecular roles, such as regulation of gene expression, splicing, or as modulators of protein activity. As reflected in the number of published primary research articles over the past 5–10 years, the spotlight has been in particular on some of the more recently discovered RNA biotypes, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). However, these are just the most recent developments in a long history of ncRNA research that extends some 60 years. Here, we describe the history of ncRNA research from the first findings of catalytically active RNA molecules in the 1950s to the discovery of pervasive transcription in genome-wide transcriptome studies, and the current state of research. We go on to describe and define the different classes of ncRNAs based on size and provide some examples of their functions in the cell.