SWISS-MODEL is an automated system for generating 3D protein structures using homology modelling. It provides reliable models without requiring complex software or large databases. The latest version includes an improved pipeline that uses model quality estimation to select the best templates and estimate model accuracy. The system allows users to search for templates, cluster them by sequence similarity, compare structures, and select suitable templates for model building. It also supports the modelling of oligomeric structures and includes information on ligands and cofactors. The SWISS-MODEL Template Library (SMTL) contains experimentally determined protein structures and provides annotations for quaternary structures and ligands. The system uses sensitive sequence search tools and allows users to manually select templates. The accuracy of models is assessed using QMEAN scores and global quality estimates. The system is continuously evaluated by the CAMEO project, which compares SWISS-MODEL's performance with other structure prediction servers. The new web interface allows interactive template selection and comparison, and provides detailed model information for users. The system is available at http://swissmodel.expasy.org/.SWISS-MODEL is an automated system for generating 3D protein structures using homology modelling. It provides reliable models without requiring complex software or large databases. The latest version includes an improved pipeline that uses model quality estimation to select the best templates and estimate model accuracy. The system allows users to search for templates, cluster them by sequence similarity, compare structures, and select suitable templates for model building. It also supports the modelling of oligomeric structures and includes information on ligands and cofactors. The SWISS-MODEL Template Library (SMTL) contains experimentally determined protein structures and provides annotations for quaternary structures and ligands. The system uses sensitive sequence search tools and allows users to manually select templates. The accuracy of models is assessed using QMEAN scores and global quality estimates. The system is continuously evaluated by the CAMEO project, which compares SWISS-MODEL's performance with other structure prediction servers. The new web interface allows interactive template selection and comparison, and provides detailed model information for users. The system is available at http://swissmodel.expasy.org/.