A database of protein domain structure annotations for protein sequences. Domains are predicted using a library of profile HMMs from 2737 CATH superfamilies. The current Gene3D (v14) release has expanded its domain assignments to approximately 20 000 cellular genomes and over 43 million unique protein sequences. Amongst other updates, we have improved our Functional Family annotation method. We have also improved the quality and coverage of our 3D homology modelling pipeline of predicted CATH domains. Additionally, the structural models have been expanded to include an extra model organism (Drosophila melanogaster).