PDBsum is a web-based resource that provides detailed information about protein structures derived from the Protein Data Bank (PDB). It offers a variety of visualizations, including 2D diagrams and 3D models, to help users understand the relationships between protein sequences, structures, and functions. The database includes annotations on protein-protein interactions, ligand binding sites, and functional sites, making it a valuable tool for researchers in the fields of biochemistry and molecular biology. Users can easily access summaries of individual protein entries, facilitating the study of protein characteristics and their biological significance.