This document discusses several important databases and tools for protein structure and molecular modeling. It describes the Protein Data Bank (PDB) as a repository for 3D structural data of proteins and nucleic acids. It also outlines the National Center for Biotechnology Information (NCBI) and its Molecular Modeling Database (MMDB), which contains experimentally resolved protein structures from PDB with additional features. Other databases and tools mentioned include UniProt, ExPASy, BLAST, and their uses in analyzing protein sequences, structures, functions, and evolutionary relationships.