The UniProt Consortium, comprising groups from the European Bioinformatics Institute (EBI), the Swiss Institute of Bioinformatics (SIB), and the Protein Information Resource (PIR), maintains the UniProt database, a comprehensive and stable resource for protein sequence and functional annotation. UniProt is composed of four main components: the UniProt Archive (UniParc), the UniProt Knowledgebase (UniProtKB), the UniProt Reference Clusters (UniRef), and the UniProt Metagenomic and Environmental Sequences database (UniMES). These components are optimized for different uses, with UniProtKB serving as the central access point for integrated protein information, UniParc as a comprehensive sequence repository, UniRef providing clustered sequences for faster searches, and UniMES addressing the expanding area of metagenomic data. UniProt is updated and distributed every 3 weeks and is freely accessible online. The consortium focuses on manual annotation, model organism-oriented annotation, and integration with other databases to enhance the quality and utility of the resource. UniProt also supports various controlled vocabularies and enzyme nomenclature to improve data consistency and interoperability. The consortium welcomes user feedback and provides extensive documentation and tools for data exploration and analysis.The UniProt Consortium, comprising groups from the European Bioinformatics Institute (EBI), the Swiss Institute of Bioinformatics (SIB), and the Protein Information Resource (PIR), maintains the UniProt database, a comprehensive and stable resource for protein sequence and functional annotation. UniProt is composed of four main components: the UniProt Archive (UniParc), the UniProt Knowledgebase (UniProtKB), the UniProt Reference Clusters (UniRef), and the UniProt Metagenomic and Environmental Sequences database (UniMES). These components are optimized for different uses, with UniProtKB serving as the central access point for integrated protein information, UniParc as a comprehensive sequence repository, UniRef providing clustered sequences for faster searches, and UniMES addressing the expanding area of metagenomic data. UniProt is updated and distributed every 3 weeks and is freely accessible online. The consortium focuses on manual annotation, model organism-oriented annotation, and integration with other databases to enhance the quality and utility of the resource. UniProt also supports various controlled vocabularies and enzyme nomenclature to improve data consistency and interoperability. The consortium welcomes user feedback and provides extensive documentation and tools for data exploration and analysis.