PDBsum is a web server that provides structural information on entries in the Protein Data Bank (PDB). It offers image-based analyses, including protein secondary structure, protein-ligand and protein-DNA interactions, PROCHECK analyses of structural quality, and more. Users can upload their own PDB files to receive password-protected PDBsum analyses. The server uses software developed by the Thornton Group, initially at University College London (UCL) and later at the European Bioinformatics Institute (EBI). PDBsum features interactive 3D structure viewing in various viewers, such as 3Dmol.js, RasMol, and PyMOL. It also includes detailed analyses like clefts, protein-protein and protein-ligand interactions, secondary structure, PROCHECK assessments, enzyme reaction diagrams, and domain architecture networks. Users can download raw data for further analysis and submit their own structures for analysis. Despite being somewhat outdated, PDBsum remains useful for its unique features, particularly the ability to submit and analyze custom structures.PDBsum is a web server that provides structural information on entries in the Protein Data Bank (PDB). It offers image-based analyses, including protein secondary structure, protein-ligand and protein-DNA interactions, PROCHECK analyses of structural quality, and more. Users can upload their own PDB files to receive password-protected PDBsum analyses. The server uses software developed by the Thornton Group, initially at University College London (UCL) and later at the European Bioinformatics Institute (EBI). PDBsum features interactive 3D structure viewing in various viewers, such as 3Dmol.js, RasMol, and PyMOL. It also includes detailed analyses like clefts, protein-protein and protein-ligand interactions, secondary structure, PROCHECK assessments, enzyme reaction diagrams, and domain architecture networks. Users can download raw data for further analysis and submit their own structures for analysis. Despite being somewhat outdated, PDBsum remains useful for its unique features, particularly the ability to submit and analyze custom structures.