It’s probably reasonable to assume that the coding sequence (CDS) of a protein-coding transcript model is the feature that is of primary interest to most people who use Ensembl. However, both the 5’ and 3’ untranslated regions (UTRs) are important biological entities in their own right, and it is vital that we in Ensembl do the best we can to represent them accurately. However, the annotation of these UTRs is complicated, so we’re going to focus on exploring the annotation process for 3’ UTRs in this article (Figure 1).