The NCBI Influenza Virus Resource provides an integrated tool for influenza virus sequence retrieval and analysis. It allows researchers to access and analyze viral sequences from around the world, which is crucial for understanding and combating influenza epidemics. The resource includes a database of influenza virus sequences, sequence analysis tools, and a genome annotation tool. The database is updated regularly and contains nucleotide and protein sequences from various influenza virus subtypes. The resource also includes tools for multiple-sequence alignment, clustering of protein sequences, and phylogenetic tree building. These tools help researchers to analyze viral sequences and understand the evolution and spread of influenza viruses. The resource is freely available to all users and has been used as the backbone of several other influenza virus sequence databases. The database is curated by an automatic procedure and NCBI staff ensure that the information is complete, accurate, and up to date. The resource also includes a genome annotation tool that helps users submit sequences to GenBank and facilitates data sharing among the influenza virus research community. The resource is supported by the Intramural Research Program of the NIH, National Library of Medicine.The NCBI Influenza Virus Resource provides an integrated tool for influenza virus sequence retrieval and analysis. It allows researchers to access and analyze viral sequences from around the world, which is crucial for understanding and combating influenza epidemics. The resource includes a database of influenza virus sequences, sequence analysis tools, and a genome annotation tool. The database is updated regularly and contains nucleotide and protein sequences from various influenza virus subtypes. The resource also includes tools for multiple-sequence alignment, clustering of protein sequences, and phylogenetic tree building. These tools help researchers to analyze viral sequences and understand the evolution and spread of influenza viruses. The resource is freely available to all users and has been used as the backbone of several other influenza virus sequence databases. The database is curated by an automatic procedure and NCBI staff ensure that the information is complete, accurate, and up to date. The resource also includes a genome annotation tool that helps users submit sequences to GenBank and facilitates data sharing among the influenza virus research community. The resource is supported by the Intramural Research Program of the NIH, National Library of Medicine.