Provides simple and universal access to interpret protein structures and sequences in light of their evolutionary variations and divergences. UET is a repository of pre-computed evolutionary trace (ET) analyses performed on the protein structure databank (PDB). UET can be accessed via a web interface using a given protein structure to retrieve an ET ranking of sequence positions and to identify functionally important regions in that structure. In UET, seamless integration of structure and phylogenetic tree viewers in the web browser means that a user can examine protein structures and sequences with their ET analyses, without any prior software installation. It also avoids access, update and digital signing issues that often plague viewers based on Java applets that run on browsers.