The Conserved Domain Database (CDD) is a resource provided by the National Center for Biotechnology Information (NCBI) for annotating proteins with conserved domain footprints. As it enters its 15th year, CDD aims to improve domain annotation coverage and consistency. The database maintains a live search system and an archive of pre-computed domain annotations for sequences in NCBI's Entrez protein database. CDD includes domain models and definitions from various public collections and an in-house curation effort, focusing on increasing coverage and providing finer-grained classifications. Recent updates to CDD include comprehensive hierarchies for various domain families and improvements in search functionality, such as higher sensitivity in domain hits and the ability to map structural motifs. The database also offers visualizations and cross-references to other NCBI resources, enhancing its utility for protein annotation and functional analysis.The Conserved Domain Database (CDD) is a resource provided by the National Center for Biotechnology Information (NCBI) for annotating proteins with conserved domain footprints. As it enters its 15th year, CDD aims to improve domain annotation coverage and consistency. The database maintains a live search system and an archive of pre-computed domain annotations for sequences in NCBI's Entrez protein database. CDD includes domain models and definitions from various public collections and an in-house curation effort, focusing on increasing coverage and providing finer-grained classifications. Recent updates to CDD include comprehensive hierarchies for various domain families and improvements in search functionality, such as higher sensitivity in domain hits and the ability to map structural motifs. The database also offers visualizations and cross-references to other NCBI resources, enhancing its utility for protein annotation and functional analysis.