PDBsum is a web server that provides structural summaries and analyses of entries in the Protein Data Bank (PDB). It offers a range of image-based analyses, including protein secondary structure, protein-ligand and protein-DNA interactions, and PROCHECK assessments of structural quality. Users can upload their own PDB files and receive password-protected analyses. The server is freely accessible at http://www.ebi.ac.uk/pdbsum. PDBsum was developed at University College London in 1995 and later transferred to the European Bioinformatics Institute (EBI) in 2001. It has since undergone several improvements. The server provides various pictorial analyses, such as surface clefts, structural superpositions, and interaction plots. It also includes domain architecture diagrams, secondary structure diagrams, and enzyme reaction diagrams. PDBsum includes features such as protein domain analysis, interaction plots, and PROCHECK analysis. It also provides information on enzyme reactions and domain architecture networks. Other analyses include calculations of protein pores and tunnels, and validation of bound ligands. PDBsum is part of several other servers, including the SAS and ArchSchema servers. It also has a user-submitted structures feature, allowing users to upload their own structures for analysis. The server is freely available and provides a comprehensive set of analyses for PDB entries. Despite its usefulness, PDBsum has some limitations, such as its inability to process very large structures due to the limitations of the PDB format. Users are redirected to other servers for such cases. PDBsum remains a valuable resource for structural biology, offering unique features and analyses that complement other servers.PDBsum is a web server that provides structural summaries and analyses of entries in the Protein Data Bank (PDB). It offers a range of image-based analyses, including protein secondary structure, protein-ligand and protein-DNA interactions, and PROCHECK assessments of structural quality. Users can upload their own PDB files and receive password-protected analyses. The server is freely accessible at http://www.ebi.ac.uk/pdbsum. PDBsum was developed at University College London in 1995 and later transferred to the European Bioinformatics Institute (EBI) in 2001. It has since undergone several improvements. The server provides various pictorial analyses, such as surface clefts, structural superpositions, and interaction plots. It also includes domain architecture diagrams, secondary structure diagrams, and enzyme reaction diagrams. PDBsum includes features such as protein domain analysis, interaction plots, and PROCHECK analysis. It also provides information on enzyme reactions and domain architecture networks. Other analyses include calculations of protein pores and tunnels, and validation of bound ligands. PDBsum is part of several other servers, including the SAS and ArchSchema servers. It also has a user-submitted structures feature, allowing users to upload their own structures for analysis. The server is freely available and provides a comprehensive set of analyses for PDB entries. Despite its usefulness, PDBsum has some limitations, such as its inability to process very large structures due to the limitations of the PDB format. Users are redirected to other servers for such cases. PDBsum remains a valuable resource for structural biology, offering unique features and analyses that complement other servers.